tree-sitter-cli: build: add support for git submodules (#422)
tree-sitter-cli: build: add support for git submodules (#422)

The .git file can contain a reference to the actual git directory as is commonly the case for a submodule[1]. When this is the case, read the .git file to discover the actual git directory.

 * cli/build.rs: Read the .git file to discover the git directory

[1] https://git-scm.com/docs/gitrepository-layout
tree-sitter/tree-sitter,tree-sitter/tree-sitter,tree-sitter/tree-sitter,tree-sitter/tree-sitter,tree-sitter/tree-sitter,tree-sitter/tree-sitter,tree-sitter/tree-sitter