[TASK] Revert "[FEATURE] Introduce client-side templating engine"

This reverts commit 6558a6bd.

The client side template engine introduced in #91810 is inspired
by lit-html. It was introduced because ES6 modules like lit-html could
not be included in core AMD builds.
With the help of rollup, lit-html can be converted to AMD within
our build process. Therefore our own implementation is removed
in order for lit-html to be introduced afterwards.

Resolves: #93058
Reverts: #91810
Releases: master
Change-Id: I2d5d20a6f9e0c8c4c683dafb6e36500f1966bd35
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/67095


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Oliver Hader <oliver.hader@typo3.org>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Benni Mack <benni@typo3.org>