[TASK] Remove dummy files from ext:tstemplate_* extensions

* Remove dummy files from ext:tstemplate_* extensions
* Remove old class names to the new ones
* Adjust function names for the backend module
* Adjust AJAX save type

Change-Id: I560c1c0e7bceb271eaba1a1d660cec71614df64a
Resolves: #48157
Related: #47756
Releases: 6.2
Reviewed-on: https://review.typo3.org/20766
Reviewed-by: Anja Leichsenring
Tested-by: Anja Leichsenring
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn
[FEATURE] Backport Object Type Converter from Flow

In Flow there is a Type Converter which can map array sources
to not persistent objects. This is very useful if you need
transitional objects built from request arguments.

Backporting this converter needs some minor modifications
in the reflection service, which are included in this commit
as well as registering the new converter.

Resolves: #48548
Releases: 6.2

Change-Id: Ic88b732076ae19ece490cf1376b2d1bbcaf1ebff
Reviewed-on: https://review.typo3.org/21114
Reviewed-by: Anja Leichsenring
Tested-by: Anja Leichsenring
Reviewed-by: Daniel Hürtgen
Tested-by: Daniel Hürtgen
Reviewed-by: Helmut Hummel
Tested-by: Helmut Hummel
[TASK] Bring back int_from_ver

Due to many failing extensions relying on this function,
Release Management decided to bring it back as a redirect
to VersionNumberUtility::convertVersionNumberToInteger.

Resolves: #48536
Relates: #44763
Releases: 6.2, 6.1
Change-Id: Id76758c10a542bdbe0cc033466f494b0a6350692
Reviewed-on: https://review.typo3.org/21047
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn
Reviewed-by: Daniel Hürtgen
Tested-by: Daniel Hürtgen
Reviewed-by: Helmut Hummel
Tested-by: Helmut Hummel