Add a do autocompletion

[axelson]

For some clients typing do will result in autocompletion which is typically not what the developer wants, an example autocompletion is defoverridable. So this PR works around that by adding do as an autocompletion when the exact text entered is "do".

I'm curious if anyone has any better/different ideas on how to solve this.

[brianalexander]

Talk about a timely issue. Was just going to look this up! defoverridable is the bane of my existence right now.

[lukaszsamson]

Unfortunately that's one of the cons of fuzzy matching

[nshafer]

It would be nice if it also indented, so insert_text: "do\n$0\nend" probably needs to be insert_text: "do\n\t$0\nend"

[axelson]

@nshafer I experimented with that a bit, but correct indentation will depend on how indented the original code is which won't always be a single level. We might be able to add some more smartness in the future but I'm not sure what form that would take.

[nshafer]

Ahh, I figured that since the carriage return results in the cursor being on the same line as whatever started the do, I thought just adding one \t would then indent whatever amount the user has configured for that file. I've had this User Snippet for a month or two now, and it seems to work reliably. Of course, it's probably totally different in the language server.

	"do_block": {
		"prefix": "do",
		"body": [
			"do",
			"\t$0",
			"end"
		]
	}