[BUGFIX] Ensure proper quoting of fields for PostgreSQL in JsonRenderer.ts

PostgreSQL requires mixed case column names in the database to be quoted at
all times, otherwise the name of the column will be forcefully converted to
all lowercase.

Set a constant in the testrenderer that contains the current database type
and switch the WHERE condition in JsonRenderer.ts to a properly quoted
version for PostgreSQL

Change-Id: I0b7caf4b51006bdf3bc131d995b0993504f49889
Releases: master
Resolves: #79651
Reviewed-on: https://review.typo3.org/51569


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Tymoteusz Motylewski <t.motylewski@gmail.com>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>