SSO: switch from module codebase to Connection package, part 3 (#37153)

* SSO: remove references to Jetpack class

* Switch to modern display of notice and add missing i18n wrapping

* Load SSO feature from the Connection package

* Switch to Connection package for all SSO references

* Deprecate all module classes and methods

* Remove module test

* Remove test reference too

* Remove one more test directory (multisite)

* Update Phan config

* Move SSO callables to the Connection package

See https://github.com/Automattic/jetpack/pull/37153/files#r1586113523

* Add deprecated class back

Co-authored-by: sergeymitr <[email protected]>

* Remove deprecated private methods

See https://github.com/Automattic/jetpack/pull/37153/files#r1586438953

Co-authored-by: sergeymitr <[email protected]>

* Remove private properties and methods

See Automattic/jetpack#37153 (comment)

Co-authored-by: sergeymitr <[email protected]>

* Move user generation to Utils class

See Automattic/jetpack#37153 (comment)

* Try fixing tests

* Revert "Try fixing tests"

This reverts commit 0ea30ae53034e025fa3e7938470991b65d254204.

* Bump versions

* Ensure the SSO module is used in tests

* Add new SSO XML-RPC method

* Jetpack Connection: Bump package version

---------

Co-authored-by: sergeymitr <[email protected]>
Co-authored-by: Foteini Giannaropoulou <[email protected]>

Committed via a GitHub action: https://github.com/Automattic/jetpack/actions/runs/9080205827

Upstream-Ref: Automattic/jetpack@101ddb3

composer.json

@@ -11,7 +11,7 @@
 		"automattic/jetpack-backup-helper-script-manager": "^0.2.6",
 		"automattic/jetpack-composer-plugin": "^2.0.1",
 		"automattic/jetpack-config": "^2.0.2",
-		"automattic/jetpack-connection": "^2.8.0",
+		"automattic/jetpack-connection": "^2.8.1-alpha",
 		"automattic/jetpack-identity-crisis": "^0.18.6",
 		"automattic/jetpack-my-jetpack": "^4.23.2",
 		"automattic/jetpack-sync": "^2.16.2-alpha",