Activate extension for cabal files only if the used hls version supports it

[jneira]

• From https://github.com/haskell/vscode-haskell/pull/417#issuecomment-889721920 and https://github.com/haskell/vscode-haskell/pull/417#issuecomment-889801291
• As commented there even if we have a hls version with support, to not throw errors to users of older versions
• We have to wait to a hls version with https://github.com/haskell/haskell-language-server/pull/2047 (with the condition we could add when th pr is is master)
• The new 1.5.0 release will no include the inclusion of .cabal files

[jneira]

Hmm you are rigth, thanks for noting it. Could we do some change in the hls part (or the extension) to avoid those errors? To investigate. Will do a release without this change in the meanwhile.

I think we can check in the vscode plugin for the version of the hls and hls-wrapper version to launch and conditionally enable loading of cabal files.

@fendor that is a good solution but it would apply only to some version of the vscode extension and not for other editors (so they will have those errors for older hls versions if they enable them like here) So not sure if it worths look for a solution in hls, where those errors will start to be emitted.

[jneira]

I've reverted the tracking of .cabal files temporary in #444 (91e9738)