fix(UX-1242): Fixed extended app bar alignment

[mikecoomber]

refactor: App bar variants are now constructed through named constructors.
fix(UX-1207): The search box on the search app bar now gets closed when the back button is pressed.
refactor: Search app bars can no longer be extended app bars.
test: Wrote tests for ZetaTopAppbar
chore: Merged goldenTest and goldenTestWithCallbacks. Also made the widgetType parameter optional and defaulted it to the type of widget.

[github-actions]

PR Checks complete

• ✅ - Linting / Formatting
• ✅ - Static analysis passed
• ✅ - All tests passed
• ✅ - Branch is not behind
• 📈 - Code coverage: 41.26% (⬆️ up from 39.34%)
  
  See details

  File Name	%	Passing?
  lib/src/components/stepper_input/stepper_input.dart	71.9%	⛔️
  lib/generated/tokens/primitives.g.dart	28.4%	⛔️
  lib/generated/tokens/semantics.g.dart	9.7%	⛔️
  lib/src/components/accordion/accordion.dart	100%	✅
  lib/src/utils/rounded.dart	100%	✅
  lib/src/components/avatars/avatar.dart	94.3%	✅
  lib/src/components/badges/indicator.dart	98.5%	✅
  lib/src/components/badges/label.dart	100%	✅
  lib/src/components/badges/priority_pill.dart	100%	✅
  lib/src/components/badges/status_label.dart	100%	✅
  lib/src/components/badges/tag.dart	98.5%	✅
  lib/src/components/banner/banner.dart	87.8%	⛔️
  lib/src/components/bottom sheets/bottom_sheet.dart	0%	⛔️
  lib/src/components/bottom sheets/menu_items.dart	0%	⛔️
  lib/src/components/breadcrumbs/breadcrumbs.dart	0%	⛔️
  lib/src/components/button_group/button_group.dart	0%	⛔️
  lib/src/components/buttons/button.dart	97.6%	✅
  lib/src/components/buttons/button_style.dart	100%	✅
  lib/src/components/buttons/icon_button.dart	51.2%	⛔️
  lib/src/components/buttons/input_icon_button.dart	72.7%	⛔️
  lib/src/components/chat_item/chat_item.dart	98.4%	✅
  lib/src/components/checkbox/checkbox.dart	100%	✅
  lib/src/components/chips/assist_chip.dart	0%	⛔️
  lib/src/components/chips/chip.dart	72%	⛔️
  lib/src/components/chips/filter_chip.dart	0%	⛔️
  lib/src/components/chips/input_chip.dart	0%	⛔️
  lib/src/components/comms_button/comms_button.dart	82%	⛔️
  lib/src/components/contact_item/contact_item.dart	0%	⛔️
  lib/src/components/date_input/date_input.dart	0%	⛔️
  lib/src/components/dial_pad/dial_pad.dart	100%	✅
  lib/src/components/dialog/dialog.dart	0%	⛔️
  lib/src/components/dropdown/dropdown.dart	0%	⛔️
  lib/src/components/fabs/fab.dart	96.4%	✅
  lib/src/components/filter_selection/filter_selection.dart	0%	⛔️
  lib/src/components/global_header/global_header.dart	0%	⛔️
  lib/src/components/global_header/header_tab_item.dart	0%	⛔️
  lib/src/components/icon/icon.dart	100%	✅
  lib/src/components/in_page_banner/in_page_banner.dart	100%	✅
  lib/src/components/list_item/dropdown_list_item.dart	0%	⛔️
  lib/src/components/list_item/list_item.dart	0%	⛔️
  lib/src/components/list_item/notification_list_item.dart	0%	⛔️
  lib/src/components/navigation bar/navigation_bar.dart	0%	⛔️
  lib/src/components/navigation_rail/navigation_rail.dart	0%	⛔️
  lib/src/components/pagination/pagination.dart	0.6%	⛔️
  lib/src/components/password/password_input.dart	100%	✅
  lib/src/components/phone_input/phone_input.dart	0%	⛔️
  lib/src/components/progress/progress_bar.dart	0%	⛔️
  lib/src/components/progress/progress_circle.dart	0%	⛔️
  lib/src/components/radio/radio.dart	0%	⛔️
  lib/src/components/screen_header_bar/screen_header_bar.dart	0%	⛔️
  lib/src/components/search_bar/search_bar.dart	98.1%	✅
  lib/src/components/segmented_control/segmented_control.dart	0%	⛔️
  lib/src/components/select_input/select_input.dart	0%	⛔️
  lib/src/components/slider/slider.dart	82.3%	⛔️
  lib/src/components/snack_bar/snack_bar.dart	0%	⛔️
  lib/src/components/stepper/stepper.dart	0%	⛔️
  lib/src/components/switch/zeta_switch.dart	0%	⛔️
  lib/src/components/tabs/tab.dart	0%	⛔️
  lib/src/components/tabs/tab_bar.dart	0%	⛔️
  lib/src/components/text_input/text_input.dart	0%	⛔️
  lib/src/components/time_input/time_input.dart	0%	⛔️
  lib/src/components/tooltip/tooltip.dart	98.9%	✅
  lib/src/components/top_app_bar/top_app_bar.dart	85.7%	⛔️
  lib/src/interfaces/form_field.dart	81.4%	⛔️
  lib/src/components/text_input/internal_text_input.dart	72.5%	⛔️
  lib/src/components/list_item/list_scope.dart	0%	⛔️
  lib/src/components/phone_input/countries.dart	10%	⛔️
  lib/src/components/progress/progress.dart	0%	⛔️
  lib/src/components/switch/material_switch.dart	0%	⛔️
  lib/src/components/text_input/hint_text.dart	77.8%	⛔️
  lib/src/components/text_input/input_label.dart	0%	⛔️
  lib/src/components/top_app_bar/extended_top_app_bar.dart	93.9%	✅
  lib/src/components/top_app_bar/search_top_app_bar.dart	88%	⛔️
  lib/src/theme/breakpoints.dart	100%	✅
  lib/src/theme/color_extensions.dart	100%	✅
  lib/src/theme/color_swatch.dart	77.3%	⛔️
  lib/src/theme/contrast.dart	100%	✅
  lib/src/theme/color_scheme.dart	100%	✅
  lib/src/theme/colors.dart	100%	✅
  lib/src/theme/theme_data.dart	100%	✅
  lib/src/theme/tokens.dart	50%	⛔️
  lib/src/utils/debounce.dart	100%	✅
  lib/src/utils/extensions.dart	100%	✅
  lib/src/utils/nothing.dart	100%	✅
  lib/src/utils/platform/platform_is.dart	10%	⛔️
  lib/src/utils/platform/universal_platform_vm.dart	21.4%	⛔️
  lib/src/utils/zeta.dart	97.8%	✅
  lib/src/utils/zeta_provider.dart	100%	✅

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[github-actions]

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