fix: Add coverage check and more samples for OpenSCAD

[nbacquey]

Description

This PR adds the missing coverage checks for OpenSCAD, and adds extra code samples to complete query coverage.

Note: according to my LSP, the following snippet isn't correct OpenSCAD, but the tree-sitter grammar parses it correctly, so I still included it in the PR:

let (a = 1, b = 2,) {};

@mkatychev do you have an opinion on the matter?

Checklist

Checklist before merging, wherever relevant:

• CHANGELOG.md updated
• README.md up-to-date

[Xophmeister]

LGTM 👍 Just waiting on the CI's opinion...

[mkatychev]

@nbacquey thanks for the heads up, I added this coverage in #859 but the PR is being held back due to a technical issue.

Note: according to my LSP, the following snippet isn't correct OpenSCAD, but the tree-sitter grammar parses it correctly

I'm assuming you're talking about openscad-LSP, the grammar correctness for the lsp uses tree-sitter-openscad as a crate, I've since added many more edge cases to handle what is technically correct grammar, compiling openscad-lsp with
tree-sitter-openscad.git = https://github.com/mkatychev/tree-sitter-openscad in the Cargo.toml should fix the warnings.

Pinging @Leathong about the grammar changes in my fork of the grammar.

EDIT: filed an issue about it
Leathong/openscad-LSP#35