feat(eslint-plugin): [prefer-readonly-parameter-types] add option treatMethodsAsReadonly

[RebeccaStevens]

fix #1758

[typescript-eslint]

Thanks for the PR, @RebeccaStevens!

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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Nx Cloud Report

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	nx test @typescript-eslint/eslint-plugin-tslint
	nx test @typescript-eslint/eslint-plugin
	nx test @typescript-eslint/eslint-plugin-tslint
	nx test @typescript-eslint/eslint-plugin
	nx test @typescript-eslint/eslint-plugin-internal
	nx test @typescript-eslint/eslint-plugin-tslint
	nx test @typescript-eslint/eslint-plugin
	nx run-many --target=typecheck --all --parallel
	nx test @typescript-eslint/parser
	nx test @typescript-eslint/experimental-utils
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	nx test @typescript-eslint/visitor-keys
	nx test @typescript-eslint/typescript-estree
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	nx run-many --target=build --all --parallel
	nx test @typescript-eslint/parser
	nx test @typescript-eslint/experimental-utils
	nx test @typescript-eslint/scope-manager
	nx test @typescript-eslint/visitor-keys
	nx test @typescript-eslint/typescript-estree

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[codecov]

Codecov Report

Merging #3733 (8159ec0) into master (5696407) will decrease coverage by 0.86%.
The diff coverage is 100.00%.

❗ Current head 8159ec0 differs from pull request most recent head af431ed. Consider uploading reports for the commit af431ed to get more accurate results

@@            Coverage Diff             @@
##           master    #3733      +/-   ##
==========================================
- Coverage   93.55%   92.68%   -0.87%     
==========================================
  Files         147      327     +180     
  Lines        7869    11354    +3485     
  Branches     2493     3202     +709     
==========================================
+ Hits         7362    10524    +3162     
- Misses        162      369     +207     
- Partials      345      461     +116     

Flag	Coverage Δ
unittest	92.68% <100.00%> (-0.87%)	⬇️

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

Impacted Files	Coverage Δ
...lugin/src/rules/prefer-readonly-parameter-types.ts	100.00% <100.00%> (ø)
packages/eslint-plugin/src/util/isTypeReadonly.ts	97.14% <100.00%> (+2.93%)	⬆️
packages/eslint-plugin/src/rules/dot-notation.ts	92.30% <0.00%> (ø)
...t-plugin/src/rules/prefer-reduce-type-parameter.ts	100.00% <0.00%> (ø)
packages/scope-manager/src/lib/base-config.ts	100.00% <0.00%> (ø)
...experimental-utils/src/eslint-utils/RuleCreator.ts	66.66% <0.00%> (ø)
...plugin-internal/src/rules/prefer-ast-types-enum.ts	90.00% <0.00%> (ø)
packages/typescript-estree/src/convert.ts	98.27% <0.00%> (ø)
.../experimental-utils/src/ts-eslint-scope/analyze.ts	100.00% <0.00%> (ø)
packages/scope-manager/src/scope/FunctionScope.ts	92.30% <0.00%> (ø)
... and 175 more

[bradzacher]

LGTM - thanks for this!