todo: enable `NoUncheckedIndexedAccess` TS compiler option

[AZMCode]

I'm aware this is a controversial topic, however I would find it useful if Deno's std library was compatible with Typescript's new noUncheckedIndexedAccess flag, since I find my projects that use it severely handicapped. I believe dropping some assertions throughout the code (after patching assert itself), or using less indexes should be enough.

[kitsonk]

@kt3k this belongs in deno_std as it is requesting that the std library compile without diagnostics with the noUncheckedIndexedAccess flag is set to true. Similar to the std library being strict safe, etc. It has nothing to do with the Deno CLI itself.

[kt3k]

@kitsonk Ah, I misread the issue.. Moving back to std.

[kitsonk]

My personal opinion is that I don't mind having noUncheckedIndexedAccess "clean" code for std, I just wouldn't want to make it the default for the Deno CLI.

[iuioiua]

I think we should add this. PRs are welcome!

[iuioiua]

Closing this in favour of #4040. Thank you for the input, guys!