[Feature] Support toggling CMake bracket comments in VS Code

### Request Overview

CMake Tools registers only lineComment: "#" in its VS Code language
configuration. CMake supports bracket comments #[[ ... ]], but VS Code's
Toggle Block Comment command does nothing.

Suggested fix in src/extension.ts:

comments: {
lineComment: "#",
blockComment: ["#[[", "]]"]
}

### Additional Information

_No response_

Open src/extension.ts and find the CMake language configuration's comments entry. Add support for the bracket comment delimiters described in the issue, then verify in VS Code that Toggle Block Comment works for CMake #[[ ... ]] comments while line comments still use #.

Written by the indexing model from the issue text.