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%)	⬇️