The template json client was failing to start in vscode insiders (1.47) because the json language server code in the included vscode.json-language-features extension changed.
This changes the template extension to use a fixed version of vscode-json-languageserver so we have more control over out interaction with it.
It also fixes the test:vscode-insiders-integration to work again and adds it to the github actions ci builds so we'll know about any failures in the next version of vscode faster.
The template json client was failing to start in vscode insiders (1.47) because the json language server code in the included vscode.json-language-features extension changed. This changes the template extension to use a fixed version of vscode-json-languageserver so we have more control over out interaction with it. It also fixes the test:vscode-insiders-integration to work again and adds it to the github actions ci builds so we'll know about any failures in the next version of vscode faster.