[BUGFIX] Fix TypeScript compilation on case insensitive file systems

With the TypeScript source move in #96906 one file hasn't been
moved into the correct place, causing operating systems with case
insensitive file systems like MacOS to merge Input/index.d.ts
and input/clearable.ts into one folder called "Input/". This causes
the compilation to fail. Move the index.d.ts in to the new folder.

Resolves: #96927
Related: #96906
Releases: main
Change-Id: If1eb46a059c2f99eeb20613a52c30bab76b4f5df
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/73562
Tested-by: Oliver Bartsch <bo@cedev.de>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Benni Mack <benni@typo3.org>
Tested-by: Benjamin Franzke <bfr@qbus.de>
Reviewed-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Benni Mack <benni@typo3.org>
Reviewed-by: Benjamin Franzke <bfr@qbus.de>