JPMT-28 Connection: add provider-specific authentication endpoints (#42602)

* Add provider-specific authorization URL endpoint for Jetpack connection

* changelog

* Add support for magic link authentication and update provider options

* Replace string-based URL manipulation with proper URL parsing and construction for provider-specific authentication endpoints.

* Update doc, bring back $raw parameter

* Refactor email address assignment using null coalescing operator

* Update permission callback to use the correct method and handle optional redirect URI and email address parameters

* Refactor email address handling in magic link flow and ensure URL parameter values are properly encoded

* Add unit tests for provider-specific authentication endpoints

* Fix phan warning

Committed via a GitHub action: https://github.com/Automattic/jetpack/actions/runs/14000537385

Upstream-Ref: Automattic/jetpack@96b2fa3

Author: Initsogar

composer.json

@@ -9,7 +9,7 @@
 		"automattic/jetpack-blocks": "^3.0.8-alpha",
 		"automattic/jetpack-calypsoify": "^0.2.2-alpha",
 		"automattic/jetpack-classic-theme-helper": "^0.11.5-alpha",
-		"automattic/jetpack-connection": "^6.7.7",
+		"automattic/jetpack-connection": "^6.8.0-alpha",
 		"automattic/jetpack-masterbar": "^0.14.2-alpha",
 		"automattic/jetpack-redirect": "^3.0.5",
 		"automattic/jetpack-stats-admin": "^0.24.6-alpha",