docs(ast): add more docs for JS expressions, declarations, and module AST types (#8800)

Tried to add documentation and examples for as many of the remaining AST
methods as I could. There are still around 30 or so remaining in this
file, but this PR adds around 50 documentation comments.

I tried my best to check that each comment is correct, but I was
inferring from the source and usage, so it may not be 100% accurate.
Please take a quick look over the comments and see if it looks right.

Co-authored-by: camchenry <1514176+camchenry@users.noreply.github.com>

Author: camchenry