Add more information to analysis.Diagnostic

[jribbink]

Issue to be solved

Currently analysis.Diagnostic only contains information regarding:

• Messaging
• Fixes
• Location
• A black box "category" field

In order to provide more robust diagnostic information to users, it would be helpful to extend this struct and add the following

• URL to documentation
• An error code (needed by LSP to link to documentation & useful to categorize/identify diagnostics when looking for solutions, documentation, help, etc)
• Severity field

While certain tooling (LS) does use the "Category" field to resolve a severity, it is somewhat limiting and there are benefits to a more generalized approach:

• Analyzers cannot define severity on a per-diagnostic basis
• Diagnostic categories are not necessarily standardized and it may not be entirely clear to the consumer which category maps to which severity level/which diagnostic categories exist

Suggested Solution

No response