Partially fixes #1482. This PR completes the fourth step of the Jetpack sign in with self credentials as defined in the master thread here. This PR adds new tracking events added as part of this feature.

Events

• LOGIN_NO_JETPACK_SCREEN_VIEWED - The no jetpack available screen is loaded.
• LOGIN_NO_JETPACK_VIEW_INSTRUCTIONS_BUTTON_TAPPED - User tapped on the "View Instructions" button on the no jetpack available screen.
• LOGIN_NO_JETPACK_LOGOUT_LINK_TAPPED - User tapped on the "Logout" link on the no jetpack available screen.
• LOGIN_NO_JETPACK_TRY_AGAIN_TAPPED - User tapped on the "Try again" button on the no jetpack available screen.
• LOGIN_NO_JETPACK_MENU_HELP_TAPPED - User tapped on the Help menu button on the no jetpack available screen.
• LOGIN_DISCOVERY_ERROR_SCREEN_VIEWED - The discovery error screen is loaded.
• LOGIN_DISCOVERY_ERROR_TROUBLESHOOT_BUTTON_TAPPED - User tapped on the "Read our troubleshooting tips" button on the discovery error screen.
• LOGIN_DISCOVERY_ERROR_TRY_AGAIN_TAPPED - User tapped on the "Try again" button on the discovery error screen.
• LOGIN_DISCOVERY_ERROR_SIGN_IN_WORDPRESS_BUTTON_TAPPED - User tapped on the "Sign in with wordpress" button on the discovery error screen.
• LOGIN_DISCOVERY_ERROR_MENU_HELP_TAPPED - User tapped on the Help menu button on the on the discovery error screen.
• LOGIN_MAGIC_LINK_INTERCEPT_SCREEN_VIEWED - The magic link intercept screen is viewed. This is the view that is displayed when the user clicks on a magic link from their device.
• LOGIN_MAGIC_LINK_INTERCEPT_RETRY_TAPPED - User tapped on the "Retry" button on the magic link intercept screen. This button is only displayed when the user account, user account settings or the site list could not be fetched.
• LOGIN_MAGIC_LINK_UPDATE_TOKEN_FAILED - The request submitted to update the magic link token to the FluxC cache has failed.
• LOGIN_MAGIC_LINK_FETCH_ACCOUNT_FAILED - The request submitted to fetch user account info from the API has failed.
• LOGIN_MAGIC_LINK_FETCH_ACCOUNT_SETTINGS_FAILED - The request submitted to fetch user account settings from the API has failed.
• LOGIN_MAGIC_LINK_FETCH_SITES_FAILED - The request submitted to fetch sites belonging to the user account from the API has failed.
• LOGIN_MAGIC_LINK_FETCH_ACCOUNT_SUCCESS - The request submitted to fetch user account info from the API was successful.
• LOGIN_MAGIC_LINK_FETCH_ACCOUNT_SETTINGS_SUCCESS - The request submitted to fetch user account settings from the API was successful.
• LOGIN_MAGIC_LINK_FETCH_SITES_SUCCESS - The request submitted to fetch sites belonging to the user account from the API was successful.

Notes:

- This PR is in draft till this Step 3 PR is merged.

TODO

• Add tracks events to the spreadsheet
• Validate and register the new tracks events

Update release notes:

• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.