Optimize login form & support OIDC_BTN_NAME

[finovy]

• 优化了登录界面更美观
• 修复了登录界面存在横向滚动条的问题
• 配置项新增OIDC_BTN_NAME，支持定义OIDC登录的按钮名称

[codecov]

Codecov Report

All modified lines are covered by tests ✅

Comparison is base (d4b5ea9) 75.50% compared to head (9cf2319) 75.50%.

❗ Current head 9cf2319 differs from pull request most recent head e300332. Consider uploading reports for the commit e300332 to get more accurate results

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #2324   +/-   ##
=======================================
  Coverage   75.50%   75.50%           
=======================================
  Files         107      107           
  Lines       15460    15460           
=======================================
  Hits        11673    11673           
  Misses       3787     3787           

Files	Coverage Δ
sql/views.py	64.00% <ø> (ø)

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