(wip) Trilogy adapter support

[Austio]

This PR adds the ability for teams to use trilogy instead of mysql2 for their adapter. Basic logic is this

• When we want trilogy and are rails 8.1
• Load the trilogy adapter instead of the mysql2

Due to changes in #131 and #128 it is essentially a new adapter that does very little except pass alter statements to pt-online-schema-change and ensure that add/remove index have

There is some duplication in this that i will probably pull to a concern but opting to keep separate while in WIP

Logic for the adapter selection is documented in the readme

| Option                            | Default | What it Controls                                                                                                                                                          |
|-----------------------------------|---------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| db_adapter_name                   | nil     | 'mysql2' or 'trilogy' - gives users an ability to provide the specific db adapter to override the db_adapter we use in departure see Db Adapter Support Below for details |

Db Adapter Support

Starting in Rails 8.1 we add support for the use of the trilogy database adapter gem. Logic for selecting an adapter follows this logic

1. Departure.configuration.db_adapter_name is set to 'mysql2' or 'trilogy' use that value
2. If the database configuration specifies 'mysql2 or 'trilogy' use that adapter
3. Default to mysql2

[xjunior]

Would it be a problem to support trilogy since rails 7.1?

[xjunior]

I was also wondering if it wouldn't be possible to get that from the original connection. On my original attempt to implement trilogy support I remember trying that but ended up with the configuration like you did, but I was wondering whether that wasn't possible now.

[Austio]

You can derive it from the connection, i'm not 100% there yet with this pr but once i am we can answer the pre 8.1 for complexity if someone is actually needing in rails 8.0 or before.

My initial thought is to put it in 8.1 and beyond so that as people upgrade they will be able to use it.

7.1 is EOL October 1st

[guilleiguaran]

7.1 -> 8.0 and 8.0 -> 8.1 are easy upgrades, so I won't bother about supporting previous versions.

[xjunior]

Did we forget this here in previous PRs?

[Austio]

🙈 yes my bad

[xjunior]

Why is this not needed anymore? Did this get moved to the railtie?

[Austio]

Still tinkering but hoping to pull all the registration into the railtie, if not this will have to work and go back in

[guilleiguaran]

+1 on this, a railtie is the most appropriate place for registration.