Support TypeScript nested type identifiers

[begleynk]

This type signature is not parsed correctly, because we can't parse nested types.

function verifyToken(token: string): string | jwt.JwtPayload {}
                                              --------------
                                                     ^
                                                     |
                                            This is the issue

This gets parsed as follows by tree-sitter (Paste into here: https://tree-sitter.github.io/tree-sitter/playground):

[program](https://tree-sitter.github.io/tree-sitter/playground#) [0, 0] - [1, 0]
  [function_declaration](https://tree-sitter.github.io/tree-sitter/playground#) [0, 0] - [0, 63]
    name: [identifier](https://tree-sitter.github.io/tree-sitter/playground#) [0, 9] - [0, 20]
    parameters: [formal_parameters](https://tree-sitter.github.io/tree-sitter/playground#) [0, 20] - [0, 35]
      [required_parameter](https://tree-sitter.github.io/tree-sitter/playground#) [0, 21] - [0, 34]
        pattern: [identifier](https://tree-sitter.github.io/tree-sitter/playground#) [0, 21] - [0, 26]
        type: [type_annotation](https://tree-sitter.github.io/tree-sitter/playground#) [0, 26] - [0, 34]
          [predefined_type](https://tree-sitter.github.io/tree-sitter/playground#) [0, 28] - [0, 34]
    return_type: [type_annotation](https://tree-sitter.github.io/tree-sitter/playground#) [0, 35] - [0, 60]
      [union_type](https://tree-sitter.github.io/tree-sitter/playground#) [0, 37] - [0, 60]
        [predefined_type](https://tree-sitter.github.io/tree-sitter/playground#) [0, 37] - [0, 43]
        [nested_type_identifier](https://tree-sitter.github.io/tree-sitter/playground#) [0, 46] - [0, 60]
          module: [identifier](https://tree-sitter.github.io/tree-sitter/playground#) [0, 46] - [0, 49]
          name: [type_identifier](https://tree-sitter.github.io/tree-sitter/playground#) [0, 50] - [0, 60]
    body: [statement_block](https://tree-sitter.github.io/tree-sitter/playground#) [0, 61] - [0, 63]

Note the nested_type_identifier section near the end.

The fix

This should be quite easy to add to https://github.com/Doctave/dossier/blob/main/dossier-ts/src/types.rs.

Then we need to ensure that we can resolve these types to their implementations. That may require a bit more thinking.