Missing FileSystemProvider for the 'jdt' scheme

vscode-java uses a custom URI scheme, jdt, to represent binary class files. However it only provides a TextDocumentProvider so jdt:// URIS can be opened as documents. Because vscode-java doesn't (yet) provide a FileSystem provider, vscode.workspace.fs.readFile calls on jdt URIs throw an ugly exception:

ENOPRO: No file system provider found for resource 'jdt://contents/java.base/java.lang/String.class?%3Ddemogorgon%2F%5C%2FUsers%5C%2Ffbricon%5C%2F.sdkman%5C%2Fcandidates%5C%2Fjava%5C%2F21.0.2-tem%5C%2Flib%5C%2Fjrt-fs.jar%60java.base%3D%2Fjavadoc_location%3D%2Fhttps%3A%5C%2F%5C%2Fdocs.oracle.com%5C%2Fen%5C%2Fjava%5C%2Fjavase%5C%2F21%5C%2Fdocs%5C%2Fapi%5C%2F%3D%2F%3D%2Fmaven.pomderived%3D%2Ftrue%3D%2F%3Cjava.lang%28String.class'

This affects Continue, see https://github.com/continuedev/continue/pull/5536, which also impacts Granite.Code, see https://github.com/Granite-Code/granite-code/issues/115.

vscode-java should provide a proper FileSystemProvider for the jdt scheme.

首先定位用于 jdt URI scheme 的现有 TextDocumentProvider，并跟踪 issue 中描述的 vscode.workspace.fs.readFile 调用。为 jdt URI 添加相应的 FileSystemProvider 行为，并验证这些读取操作不再抛出所报告的 ENOPRO 异常。