Replace tree-sitter submodules with Rust bindings #442

Some of the tree-sitter grammars can be used as Cargo.toml dependencies. In this way, some submodules can be removed.

Pros

• A cleaner repository
• Avoid breaks during the update of a tree-sitter grammar due to some problems in handling submodules
• Less options and commands to clone the project

Cons

• Impossibility to change the grammars directly in this repo, the grammars have to be modified upstream

Submodules languages:

• tree-sitter-java (Delete Java submodule #449)
• tree-sitter-python (Delete Python submodule #464)
• tree-sitter-cpp (Remove tree-sitter-cpp submodule #498)
• tree-sitter-rust (Delete Rust submodule #594)
• tree-sitter-javascript (Delete JavaScript submodule #463)
• tree-sitter-typescript (Delete TypeScript submodule #592)