Unstable flags not respected when running tests

[kitsonk]

Describe the bug

While #1159 provides the ability to specify granular unstable flags, those flags are not respected when running tests within the IDE, and tests requiring unstable flags no longer run in the IDE with Deno 2.0.

Also the README still indicates that the value of deno.unstable is a boolean.

To Reproduce

1. create a test that requires Deno.KV
2. configure the configuration like "deno.unstable": ["kv"]
3. Execute the test in the IDE
4. Review output of the Deno Language Server and observe:

Executing test run with arguments: deno test --allow-all --no-check --trace-leaks --unstable

Expected behavior

The test executes successfully.

Versions

vscode: 1.93.0 deno: 2.0.0-rc.1 extension: 3.40.0

[nayeemrmn]

It will only work with 2.0.0-rc.2 released tomorrow, to not break the server's expected config for earlier versions.