[TASK] Unify Rollup usage in frontend tooling

In the current frontend tooling, we invoke Rollup twice:

* via grunt-rollup to build library modules
* via the command line to build everything related to CKEditor

This commit gets rid of the first way and moves the library
compilation to a JS-backed configuration as well, so we can
get rid of a grunt package and also unify the tooling a bit.
We also make use of @rollup/plugin-terser instead of the deprecated
rollup-plugin-terser module that was used in ckeditor build before.

To match the new behaviour, the "exec:ckeditor" task also was
renamed to "exec:rollup".

Executed commands:

    npm remove grunt-rollup
    npm remove rollup-plugin-terser
    npm install @rollup/plugin-terser --save-dev
    npm run build

Resolves: #103686
Releases: main, 12.4
Change-Id: I8057dcceae2d039c637c6db68cf51b3ef1f12406
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/83942


Tested-by: Andreas Kienast <a.fernandez@scripting-base.de>
Reviewed-by: Benjamin Franzke <ben@bnf.dev>
Tested-by: Benni Mack <benni@typo3.org>
Tested-by: Benjamin Franzke <ben@bnf.dev>
Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Benni Mack <benni@typo3.org>
Reviewed-by: Andreas Kienast <a.fernandez@scripting-base.de>