Disable automatic semicolon insertion at end of object patterns

[nbrahms]

"object_type" nodes admit automatic semicolons, whereas "object_pattern"
nodes do not. The current grammar will greedily attempt to consume an
object_type node, and insert an automatic semicolon within this type:

({a}: {a: number}) => number

Since object types can never themselves be typed, I use two-token
lookahead when deciding to insert an automatic semicolon before the
closing braces of a braced sequence of tokens; if a type annotation
follows the closing brace, we will not allow an automatic semicolon.

Fixes #144.

[maxbrunsfeld]

@dcreager @patrickt Do you know why the GH actions CI isn't running on PRs? I think we had this problem with a different grammar repo.

Also, I am responsible for the windows CI failure. In 892494d, I restructured the Node and Rust bindings' structure so that the repo is installable as a single module. On Windows, my approach seems to have led to a duplicate symbol error. I will try to take a look at this soon (unless you all know anyone else who loves debugging linker errors 🤔 ). But in the meantime, I don't think it needs to block @nbrahms's PR.

I do think we should try to get a green CI run on another platform though.

[maxbrunsfeld]

Your solution makes sense to me, and you've added good test coverage. If possible, I'd like to get CI running properly before we merge.

[mjambon]

@dcreager @patrickt @maxbrunsfeld, @nbrahms was wondering what the intention was with the branch filter **:** in the GHA config. Another thing to check is whether the job would trigger when the PR is from a forked repo.