[SMALL] Split TemporalTranslations into per-type suites

[roji]

This is a simple refactor-only change that splits TemporalTranslations into different test suites.

There seem to be enough tests for each type (DateTime, DateTimeOffset...) to justify different suites... But more importantly, for some providers there are multiple mapping options: DateTime can be mapped to timestamp with time zone or timestamp without time zone on PostgreSQL, datetime or datetime2 on SQL Server, etc. This allows easily extending DateTimeTranslationsTestBase twice, once with each mapping strategy.

Continues #34872

[roji]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[roji]

@dotnet/efteam ping, this is probably the last translation test work PR for now.

[cincuranet]

LGTM in general. Assuming the The type or namespace name 'TemporalTranslationsTestBase<>' could not be found (are you missing a using directive or an assembly reference?) will get fixed.