Add action to load the sidecar plugin

[millerf]

Changes proposed in this Pull Request

• Added "sift_for_woocommerce_load_sidecar_plugin" action

Testing instructions

Mentions #

[github-actions]

Package	Line Rate	Complexity	Health
inc/payment-gateways/index.php	0%	0	❌
inc/payment-gateways/lib/stripe.php	63%	77	➖
inc/payment-gateways/load.php	0%	0	❌
inc/payment-gateways/ppcp-gateway.php	0%	18	❌
inc/payment-gateways/stripe.php	23%	17	❌
inc/payment-gateways/transact.php	100%	0	✔
inc/payment-gateways/woocommerce-payments.php	30%	8	❌
inc/sift-decisions/abuse-decisions.php	0%	14	❌
inc/sift-decisions/sift-decision-rest-api-webhooks.php	0%	10	❌
inc/sift-events/class-sift-event-types.php	100%	4	✔
inc/sift-events/normalizers/sift-order.php	96%	6	✔
inc/sift-events/normalizers/sift-payment-gateway.php	100%	5	✔
inc/sift-events/normalizers/sift-payment-method.php	97%	31	✔
inc/sift-events/normalizers/sift-payment-type.php	83%	3	✔
inc/sift-events/normalizers/sift-property.php	100%	3	✔
inc/sift-events/normalizers/sift-verification-status.php	50%	3	➖
inc/sift-events/sift-events-validator.php	85%	140	✔
inc/sift-events/sift-events.php	71%	126	➖
inc/tracking-js.php	0%	4	❌
inc/wc-admin-settings-tab.php	0%	24	❌
index.php	0%	0	❌
sift-for-woocommerce.php	14%	11	❌
Summary	55% (1030 / 1889)	504	➖

[chrisfromthelc]

LGTM