Add tracking to the site switcher

[emilylaguna]

Project: #17503

Description

Adds tracking to the site switcher when:

• The My Site Site switcher is tapped
• The site switcher is displayed
• The site switcher is dismissed
• The edit / done button is toggled
• The add site button is tapepd
• A search is performed
• A blogs visible is changed

To test:

1. Launch the app and sign in with an account with multiple blogs enabled
2. Tap the down arrow to open the site switcher:
3. Verify you see: 🔵 Tracked: my_site_site_switcher_tapped
4. Verify you see: 🔵 Tracked: site_switcher_displayed
5. Perform a search and verify you see: 🔵 Tracked: site_switcher_search_performed
6. Tap the Edit button
7. Verify you see: 🔵 Tracked: site_switcher_toggled_edit_tapped <state: edit>
8. Tap the switch button to change a blogs visibility to hidden
9. Verify you see 🔵 Tracked: site_switcher_toggle_blog_visible <blog_id: BLOG_ID, site_type: blog, visible: 0>
10. Tap the switch button to change a blogs visibility to visible
11. Verify you see 🔵 Tracked: site_switcher_toggle_blog_visible <blog_id: BLOG_ID, site_type: blog, visible: 1>
12. Tap the 'Done' button
13. Verify you see 🔵 Tracked: site_switcher_toggled_edit_tapped <state: done>
14. Tap the + button to add a site
15. Verify you see 🔵 Tracked: site_switcher_add_site_tapped
16. Tap the 'Cancel' button
17. Verify you see 🔵 Tracked: site_switcher_dismissed

Regression Notes

1. Potential unintended areas of impact
   None, adding tracks to specific areas.

2. What I did to test those areas of impact (or what existing automated tests I relied on)
   Manual testing

3. What automated tests I added (or what prevented me from doing so)
   None.

PR submission checklist:

• I have completed the Regression Notes.
• I have considered adding unit tests for my changes.
• I have considered adding accessibility improvements for my changes.
• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.

[peril-wordpress-mobile]

You can trigger an installable build for these changes by visiting CircleCI here.

[peril-wordpress-mobile]

You can trigger optional UI/connected tests for these changes by visiting CircleCI here.

[momo-ozawa]

@emilylaguna LGTM! Works as described 🚀