[LS] Add support for new analysis.Diagnostic information & CadenceV1Analyzer

[jribbink]

Closes #293

Description

This PR adds language server support for new analysis.Diagnostic information as well as assigning a different severity to Cadence V1 Analyzer diagnostics.

Dependent on:

• https://github.com/onflow/cadence/pull/3082
• https://github.com/onflow/cadence-tools/pull/285 (so we can set the severity of the diagnostics)

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• [x] Targeted PR against master branch
• [x] Linked to Github issue with discussion and accepted design OR link to spec that describes this work
• [x] Code follows the standards mentioned here
• [x] Updated relevant documentation
• [x] Re-reviewed Files changed in the Github PR explorer
• [x] Added appropriate labels

[turbolent]

Nice!