typescript-ts-mode: Improve function body indentation (bug#78121)

typescript-ts-mode: Improve function body indentation (bug#78121)

Older code was calculating body indentation depending on function
parameters alignment.  This is incorrect, because if parameters are
misaligned, so will the function body.  Instead, use offset of the
previous standalone parent.

* lisp/progmodes/typescript-ts-mode.el:
(typescript-ts-mode--indent-rules): Stop depending on function
parameters indentation for calculating body content and the closing
`}'.
* test/lisp/progmodes/typescript-ts-mode-resources/indent.erts:
(Function body with params misindented (bug#78121)): Add new test.