fix(eslint-plugin): [prefer-return-this-type] handle generics properly in fixer

[rafaelss95]

Fixes #3842.

[typescript-eslint]

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[codecov]

Codecov Report

Merging #3852 (a937297) into master (4195919) will decrease coverage by 0.00%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #3852      +/-   ##
==========================================
- Coverage   93.50%   93.50%   -0.01%     
==========================================
  Files         151      151              
  Lines        8134     8132       -2     
  Branches     2580     2579       -1     
==========================================
- Hits         7606     7604       -2     
  Misses        167      167              
  Partials      361      361              

Flag	Coverage Δ
unittest	93.50% <100.00%> (-0.01%)	⬇️

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

Impacted Files	Coverage Δ
...eslint-plugin/src/rules/prefer-return-this-type.ts	90.16% <100.00%> (-0.32%)	⬇️

[nx-cloud]

Nx Cloud Report

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

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[bradzacher]

thanks for this! - one comment

[bradzacher]

instead of doing this here - we should instead change the tryGetNameInType function to return the TSTypeReference instead of the Identifier.

[bradzacher]

LGTM - thanks for fixing this!