feat: parse variable expansion in include path

[WilsonZiweiWang]

This change should allow the parser to recognize the variable expansion syntax in the include_path.
Example from poky:
https://github.com/yoctoproject/poky/blob/348d9aba3305cd98b0c0b1ec0f4b1407e786307a/meta/recipes-core/glibc/glibc-y2038-tests_2.38.bb#L1

Sample result:

[amaanq]

thanks for the PR. it looks like a few of them fail in your screenshot output, is that intentional because of the unclosed quote? that's fine with me if so

[WilsonZiweiWang]

thanks for the PR. it looks like a few of them fail in your screenshot output, is that intentional because of the unclosed quote? that's fine with me if so

yes, I put the " after the $ so none of the choices should match.

[amaanq]

just gonna force push your generated changes using tree-sitter cli on master, otherwise LGTM

[amaanq]

thanks!