Fixes all TypeScript failures caused by enabling the `--strict`
flag for test source files. We also want to enable the strict
options for tests as the strictness enforcement improves the
overall codehealth, unveiled common issues and additionally it
allows us to enable `strict` in the `tsconfig.json` that is picked
up by IDE's.
PR Close#30993
The `renderStringify` function shows up pretty high in the CPU profiling.
Turns out that this function contained unnecessary `typeof` check for
function types - the check only makes sense / is used in error messages.
The PR also alligns how ivy and view engine stringify functions used in
interpolations.
PR Close#30838