Code navigation for new language: DM

## Language

DM (https://www.byond.com/docs/ref)

**DM**, also known as **Dream Maker**, is a programming language used in the **BYOND** RPG game engine. One of the biggest FOSS games, **Space Station 13**, is written in this language and is actively being developed. Most of the branches of the original game use the GitHub as a repository for the source code of the game. The ecosystem of the language is also mainly supported by developers of various branches of the game.

## Linguist entry

- [x] Linguist language name: DM
- [x] Linguist language ID: 83
- [x] Permalink: https://github.com/github-linguist/linguist/blob/537297cdae3ab05f8d5dd1c03627a5bd73707b19/lib/linguist/languages.yml#L1611-L1620

## Tree-sitter parser

Parser URL: https://github.com/FeudeyTF/tree-sitter-dm

- [x] Parser is open source: MIT license
- [x] Repository includes tags queries
- [ ] Tags queries include `@scope` for fully-qualified names (if applicable)
- [x] Rust crate: https://crates.io/crates/tree-sitter-dm

## Remarks

The DM programming language has been supported in GitHub Linguist since 2013, but uses only a grammar based on TextMate. Now it is possible to use a modern tree-sitter-dm parser based on the tree-sitter project.

Read the Code Navigation README section on adding a new language, then inspect the supplied Linguist language entry and the tree-sitter-dm repository. Check whether the parser, tags queries, and Rust crate meet the stated requirements; done means the DM submission is accepted for code navigation or the missing requirements are identified.

Scritto dal modello di indicizzazione a partire dal testo della issue.