Auto install dependencies

[selfint]

Install tree-sitter-cli and emscripten to extensionPath.

[selfint]

emscripten no longer needed.

[selfint]

can we remove npm and tree-sitter-cli dependencies all-together, and use only fetch?

We can get the correct tree-sitter cli binary from Tree Sitter Releases.

And we can use fetch to get the npm package instead of npm pack.