fix/#348/semicolons

[tconbeer]

Closes #348

What are the key elements of this solution?
Uses tree-sitter and tree-sitter-sql to query the document for semicolon tokens, instead of naively searching the document for semicolon strings.

Why did you design your solution this way? Did you assess any alternatives? Are there tradeoffs?
The new tree-sitter-sql is quite good, and actively maintained. This method seemed resilient even in cases where there were parsing errors thrown by tree-sitter-sql

Does this PR require a change to Harlequin's docs?

• No.
• Yes, and I have opened a PR at tconbeer/harlequin-web.
• Yes; I haven't opened a PR, but the gist of the change is: add troubleshooting page for installing tree sitter.

Did you add or update tests for this change?

• Yes.
• No, I believe tests aren't necessary.
• No, I need help with testing this change.

Please complete the following checklist:

• I have added an entry to CHANGELOG.md, under the [Unreleased] section heading. That entry references the issue closed by this PR.
• I acknowledge Harlequin's MIT license. I do not own my contribution.