Plugin for IntelliJ Platform (JetBrains IDEs)

### What is wrong?

Though Fe is an emerging language, it already has lots of established syntax constructions, so we can start building tools around it. Similar to https://github.com/ethereum/fe/issues/272, we could create an IntelliJ Platform plugin with syntax highlighting (with jump to definitions, code gen, etc. in the future).

### How can it be fixed

Vyper already has community-baked plugin https://github.com/vyperlang/vyper/issues/1444 which we could use as a reference. AFAIK Fe started as a rewrite of Vyper, so it might be handy for us.

Review the IntelliJ Platform plugin request and the linked Fe and Vyper issues, starting with the requested syntax-highlighting scope. Treat syntax highlighting as the initial milestone; jump to definitions and code generation are explicitly future work, so a complete plugin design and implementation would need a narrower plan first.

Written by the indexing model from the issue text.