fix(eslint-plugin): [@typescript-eslint/typedef] support default value for parameter

[octogonz]

Fixes #784

[typescript-eslint]

Thanks for the PR, @octogonz!

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 #785 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #785      +/-   ##
==========================================
+ Coverage    94.2%   94.21%   +<.01%     
==========================================
  Files         112      112              
  Lines        4801     4808       +7     
  Branches     1334     1334              
==========================================
+ Hits         4523     4530       +7     
  Misses        159      159              
  Partials      119      119

Impacted Files	Coverage Δ
packages/eslint-plugin/src/rules/typedef.ts	97.22% <100%> (+0.67%)	⬆️

[octogonz]

The code coverage issue was due to TSParameterProperty which was not actually getting checked by typedef. I added a commit that handles TSParameterProperty correctly.

[bradzacher]

LGTM - thanks for fixing this