refactor(language-core): remove fileName property for VirtualFile

[johnsoncodehk]

Motivation

fileName is a concept specific to TypeScript, it should not be part of the dependencies of virtual code.

Changes

• The VirtualFile interface has been renamed to VirtualCode.
• There is no longer a VirtualFile.typescript property, now you need to return the virtual code for the TypeScript LanguageService through LanguagePlugin.typescript.getScript().
• It is no longer allowed to generate multiple virtual ts files for a single file.
• ServiceEnvironment.fileNameToUri, ServiceEnvironment.uriToFileName have been moved to ServiceEnvironment.typescript.fileNameToUri, ServiceEnvironment.typescript.uriToFileName.
• The uri specific to virtual code is now [source_file_uri]?virtualCodeId=[virtual_code_id]. For example: file:///GitHub/volar-starter/src/App.vue?virtualCodeId=script

For actual changes, you can refer to: volarjs/starter@403a3d3