Format document deletes query metadata

[rvermeulen]

Describe the bug
The format document command deletes query metadata if it is the only contents of the file.

To Reproduce

1. Create a query file containing only metadata.
2. Format the document via the Format document command.

Expected behavior
Format (not as in format disk) the metadata or leave it as is.

Additional context
This is easily triggered with the option to format a document on save.

[aeisenberg]

This is a bug in the language server. I'll raise an issue there.

[rvermeulen]

Closed in favour of github/codeql-coreql-team#549