Generate changelog / Add job categories (#3239) * Add job categories Job categories are the job equivalent of [BenchmarkCategory]: they allow grouping jobs so that a subset of them can be selected, without relying on the job Id. - MetaMode.Categories, a hidden characteristic so that categories don't affect the generated job Id, the folder names, the summary nor the code generated for the child process - Job.WithCategory (adds) and Job.WithCategories (overrides), mirroring WithEnvironmentVariable...

Generate changelog / Add job categories (#3239) * Add job categories Job categories are the job equivalent of [BenchmarkCategory]: they allow grouping jobs so that a subset of them can be selected, without relying on the job Id. - MetaMode.Categories, a hidden characteristic so that categories don't affect the generated job Id, the folder names, the summary nor the code generated for the child process - Job.WithCategory (adds) and Job.WithCategories (overrides), mirroring WithEnvironmentVariable... #605