Fix dropping the PK on a PostgreSQL table with quoted name

[morozov]

Q	A
Type	bug

The issue was discovered during the work on #6589. If a table name passed to PostgreSQLPlatform#getDropIndexSQL() is quoted, it will generate invalid SQL (see the test).

The fix is a quite ugly as the code parses the provided string. This is inherent to the current platform and schema management API design where string $name can contain virtually anything (quoted or unquoted, qualified or unqualified name) and is meant to be used to in concatenation with other SQL fragments, not parsed. We will address this design issue later by making object names value objects.

[greg0ire]

Does this not affect v3? I'm on my phone and cannot check easily

[morozov]

It does, I tried to back-port but decided not to:

1. It won't cleanly rebase because of the differences in the method signature.
2. Given that the default branch in this repo is 4.2.x, I'm not sure what the support status of 3.x is.

My view is that if anyone is affected by this issue on version 3.x, they can back-port the fix.

[greg0ire]

Regarding 2. to figure if a branch is maintained, I refer to .doctrine-project.json

We usually merge things up but having people backport stuff they need makes sense, it makes the maintenance work easier.