CMS5: Make SQLite compatible

[maxime-rainville]

Acceptance criteria

• CMS5 build is green
• CMS5 build runs framework tests
• Any removed API in the CMS5 branch is marked as deprecated in the CMS4 branch
• Our CI is updated so you can install SQLite

PRs

• DEP Add silverstripe/sqlite3 recipe-kitchen-sink#35
• MNT Add changes for compatibility with CMS5 and testing with framework #69
• ENH Add support for testing alternative SQLite and preserving vendor test gha-ci#58
• BUG Update RelatedDataService to properly escape ClassName in Polymorphic relations silverstripe-framework#10713
• DEP Bump masterminds/html5 to 2.7.6 to fix deperaction warning silverstripe-framework#10714

[maxime-rainville]

Just a couple extra notes here:

• Our GitHub action CI does not currently support SQLite. Given that it's not something we actively want to support, I don't think it's worthwhile spending a lot of time getting it set up. I suggest spending 30 min to see if it's possible. If there's no obvious solution, I'm content with running the SQLite test locally and calling it a day.
• Because SQLite is a database adapter, all of its test should be covered by the ORM tests in framework.
• I recall some broken test in SQLite in CMS4. I don't think there were a big problem, so we ignored them. As long as it's mostly functional, I'm happy to merge the PR with some test failing.
• From memory, to get the module working you need to define a SS_SQLITE_DATABASE_PATH variable and set SS_DATABASE_CLASS=SQLite3Database
• The primary use case for this database adapter is to run tests. I don't thing there's anyone that actually use it to run tests.
• I had a go at creating an action that allows you to pick whatever DB adapter you want a while a ago. This is the snippet I use to install SQLite. From what I'm reading there, it looks like it's built into the GitHub action image ... so you might not need to do any sorcery to get it working.

[sabina-talipova]

silverstripe/gha-ci#58 should be merged first.