Add new semantic token types

[bstaletic]

PR Prelude

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Why this change is necessary and useful

The decorator type was introduced in LSP 1.17.
The concept type is used by clangd.

Reported by @amosnier on gitter.
The mapped value is just the first thing that came to my mind. Feel free to suggest bette alternatives.

[Please explain in detail why the changes in this PR are needed.]

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This change is 

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.22%. Comparing base (4556062) to head (f0a9213).

Additional details and impacted files

@@             Coverage Diff             @@
##           master    #4232       +/-   ##
===========================================
- Coverage   89.67%   78.22%   -11.45%     
===========================================
  Files          34       29        -5     
  Lines        4445     2760     -1685     
===========================================
- Hits         3986     2159     -1827     
- Misses        459      601      +142