Merge login lib changes and implement new interface methods

[AmandaRiu]

This PR merges the woocommerce-android changes to the login library from this PR. There were several new interface methods added existing classes:

LoginAnalyticsListener

• trackConnectedSiteInfoRequested
• trackConnectedSiteInfoFailed
• trackConnectedSiteInfoSucceeded

LoginListener

• showHelpFindingConnectedEmail
• gotConnectedSiteInfo

I've implemented these new interface methods in LoginActivity and LoginAnalyticsTracker but there is no logic needed since none of them are currently being used in WPAndroid. Those are the only two changes to WPAndroid directly.

Full documentation around the changes to login library are documented in this PR, but the WPAndroid app should see no difference in the login experience.

Recommended Test Scenarios

• Verify login flow is unchanged from the current login flow of WPAndroid
• Verify the text in each of the login views is also unchanged
• Login with email
• Login by site url
• Login w/ Magic Link
• Login w/ Google

To test:

Update release notes:

• If there are user facing changes, I have added an item to RELEASE-NOTES.txt.

[peril-wordpress-mobile]

	Warnings
⚠️	PR is not assigned to a milestone.

Messages

📖

This PR contains changes in the subtree libs/login/. It is your responsibility to ensure these changes are merged back into WordPress-Login-Flow-Android. Follow these handy steps! WARNING: Make sure your git version is 2.19.x or lower - there is currently a bug in later versions that will corrupt the subtree history! cd WordPress-Android git checkout amanda/woo-login-test-wp git subtree push --prefix=libs/login/ https://github.com/wordpress-mobile/WordPress-Login-Flow-Android.git merge/WordPress-Android/10149 Browse to https://github.com/wordpress-mobile/WordPress-Login-Flow-Android/pull/new/merge/WordPress-Android/10149 and open a new PR.

Generated by 🚫 dangerJS

[aforcier]

It looks like this branch was created with git 2.20.1 (I should've been clearer that it was still unsafe to merge anything created with that version when I suggested making a test branch, sorry).

This is what happens if you try to git subtree pull again on this branch (with a working version of git):

git subtree pull --prefix=libs/login loginlib develop --squash
remote: Enumerating objects: 1, done.
remote: Total 1 (delta 0), reused 0 (delta 0), pack-reused 1
Unpacking objects: 100% (1/1), done.
From github.com:wordpress-mobile/WordPress-Login-Flow-Android
 * branch                  develop    -> FETCH_HEAD
   78c5307f7a..6d486bbf6b  develop    -> loginlib/develop
fatal: ambiguous argument '979ddf4aec664cf9afafa1cdf7d99599488f1eee^0': unknown revision or path not in the working tree.
Use '--' to separate paths from revisions, like this:
'git <command> [<revision>...] -- [<file>...]'
could not rev-parse split hash 979ddf4aec664cf9afafa1cdf7d99599488f1eee from commit 43aef9534664821893f4a65ac7fb52b2e8c01eee
Can't squash-merge: 'libs/login' was never added.

Slacked you with updated instructions, going to close this just to be safe.