Handle typescript ts grammar breaking change for function_expression

Handle typescript ts grammar breaking change for function_expression

Starting from version 0.20.4 of the typescript/tsx grammar, "function"
becomes "function_expression". The right expression is used depending
on the grammar version.

* lisp/progmodes/typescript-ts-mode.el
(tsx-ts-mode--font-lock-compatibility-function-expression):
New function (bug#69024).
(typescript-ts-mode--font-lock-settings): Use it.

Copyright-paperwork-exempt: yes
(cherry picked from commit 9f9da26e0dcb242327af7cd8414fad7afedbbaa9)