fix(eslint-plugin): [no-use-before-define] allow class references if they're within a class decorator

[bradzacher]

Fixes #2824

[typescript-eslint]

Thanks for the PR, @bradzacher!

typescript-eslint is a 100% community driven project, and we are incredibly grateful that you are contributing to that community.

The core maintainers work on this in their personal time, so please understand that it may not be possible for them to review your work immediately.

Thanks again!

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[codecov]

Codecov Report

Merging #2827 (504f94e) into master (bf904ec) will decrease coverage by 0.01%.
The diff coverage is 80.00%.

@@            Coverage Diff             @@
##           master    #2827      +/-   ##
==========================================
- Coverage   92.74%   92.72%   -0.02%     
==========================================
  Files         309      309              
  Lines       10317    10327      +10     
  Branches     2920     2925       +5     
==========================================
+ Hits         9568     9576       +8     
- Misses        346      347       +1     
- Partials      403      404       +1     

Flag	Coverage Δ
unittest	92.72% <80.00%> (-0.02%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...es/eslint-plugin/src/rules/no-use-before-define.ts	91.11% <80.00%> (-1.39%)	⬇️