Add postgreSql Alter Column

[griffio]

closes #4163

Add the missing ALTER [COLUMN] support for PostgreSql with enough features to be useful in migration scripts.

    ALTER [ COLUMN ] column_name [ SET DATA ] TYPE data_type [ USING expression ]
    ALTER [ COLUMN ] column_name SET DEFAULT expression
    ALTER [ COLUMN ] column_name DROP DEFAULT
    ALTER [ COLUMN ] column_name { SET | DROP } NOT NULL
    ALTER [ COLUMN ] column_name ADD GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY 
    ALTER [ COLUMN ] column_name { SET GENERATED { ALWAYS | BY DEFAULT }
    ALTER [ COLUMN ] column_name DROP IDENTITY [ IF EXISTS ]
    ALTER [ COLUMN ] column_name SET ( attribute_option = value [, ... ] )

Extra 🗞️

Add into gradle build src/test/integration-postgresql-migrations - this was never enabled ❓
Fix type that was preventing migrations test to run - possibly this was why 🦺
Add integration migration test for alter table alter column
Add AlterTableAlterColumnMixin not sure what else it needs ❓

[hfhbd]

Could you add an integration test? I guess, you still need to add a mixing to alter the schema.

[hfhbd]

o_O Thanks.

[hfhbd]

Great, thank you.

[griffio]

@hfhbd can you re-trigger the build - without pushing another commit? thanks.
Otherwise - I will wait for time to rebase

Seems to be transient errors again 👺 as the build time is quite long ⏳

build (ubuntu-latest, gradle-plugin-tests)
The hosted runner: GitHub Actions 10 lost communication with the server. Anything in your workflow that terminates the runner process, starves it for CPU/Memory, or blocks its network access can cause this error.

[hfhbd]

Sure, I restarted the job.

[griffio]

Build runs fairly quickly locally 🏃 🐅

On GitHub the most recent change was to use Linux to run these tests (that should have improved build times?) - maybe try again ❔