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.

阅读 Code Navigation README 中关于添加新语言的部分，然后检查提供的 Linguist 语言条目和 tree-sitter-dm 仓库。检查 parser、tags 查询和 Rust crate 是否满足所述要求；完成意味着 DM 提交已被代码导航接受，或已识别出缺失的要求。

由索引模型根据 Issue 内容生成。