Guidance on pattern to improve context for completions in an IDE

## Background

Our IDE has an opt-in feature where it will tell copilot about all files in the current project by doing `textDocument/didOpen` on them. This could potentially be dozens, possibly even hundreds of files, given the nature of the projects in real-world use.

This was originally implemented using the vim copilot plugin, now switched to using `copilot-language-server`.

## Question

Is this a "Good Idea"? Will it actually improve completion suggestions by providing more context, or will it quickly hit some internal limit?

When I switched this to `copilot-language-server` I also implemented setting `workspaceFolders` to true, and pass the root folder of the project as the workspace folder; is that accomplishing anything in terms of improving awareness of other files in the project (i.e. does this make the "pretend to open all files" approach redundant)?

Thanks!

vim copilot plugin の動作、copilot-language-server への切り替え、および issue で説明されている workspaceFolders と textDocument/didOpen の処理を確認してください。プロジェクトのすべてのファイルを開くことで補完コンテキストが改善するのか、それとも限界に達するのかを判断し、推奨されるパターンと、workspaceFolders によってそのアプローチが不要になるかどうかを文書化してください。

索引モデルが issue の本文から書いたものです。