Add support for variables LINE_COMMENT, BLOCK_COMMENT_START…

[savetheclocktower]

…and BLOCK_COMMENT_END.

These are three of the four snippet variables that VSCode supports and we don't. You can do some nifty stuff with these, as pulsar#970's description illustrates.

The only one we don't yet support is UUID, and I've set that up so that we get it for free whenever we upgrade Electron. We are this close (imagine an index finger and a thumb very close together) to having a version of node with crypto.randomUUID; it'll basically happen whenever we upgrade Electron, even if it's a tiny bump. So I also made it so that the UUID unit tests will start running automatically as well in that scenario.

Would love to get this merged a few days before the 15th so I have time to make a PR that bumps snippets. (This is one of the very few remaining bundled packages in a separate repo — maybe the only one left? I'll have to address that soon.)

Testing

Wrote some new specs. If they pass, we're good to go.

[DeeDeeG]

I wish I understood snippets better, but I'm finding it hard to meaningfully validate this before 1.116 would happen.

I like the premise, and I'm trusting a bit that the tests are good for this feature so that it "just works", leaning on that to "rubber-stamp approve" as it were.

Again, if there are good easy steps to manually test this, I will attempt to do so. (Similar to as I mentioned in my approval of #20.)

[savetheclocktower]

I'm going to land this and the other one just so we can get it in for 1.116, but as for this:

Again, if there are good easy steps to manually test this, I will attempt to do so.

If you check out this repo, you can run ppm link . to substitute it for the built-in version. You can then add a snippet like the one described in pulsar#970 to your snippets file and verify that it works.

[savetheclocktower]

(Forgot to mention that you'd have to run Pulsar on master so that it has the new method on TextEditor that this change expects.)