[typescript] Make TypeScriptClientCodegen extend AbstractTypeScriptClientCodegen

[lwj5]

In #10080 (comment) from @wing328

modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractTypeScriptClientCodegen.java also has this line of fix but TypeScriptClient codegen class doesn't extends AbstractTypeScriptClientCodegen.java at the moment.

In the future we may consider extending TypeScriptClient class with AbstractTypeScriptClientCodegen

This makes it easier to maintain

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[lwj5]

Would appreciate if any @TiFu (2017/07) @taxpon (2017/07) @sebastianhaas (2017/07) @kenisteward (2017/07) @Vrolijkx (2017/09) @macjohnny (2018/01) @topce (2018/10) @akehir (2019/07) @petejohansonxo (2019/11) @amakhrov (2020/02) @davidgamero (2022/03) @mkusaka (2022/04)

could help to take a look at these

[macjohnny]

IIRC the typescript client codegen was meant to be a rewrite for unification of all the typescript-variants there currently are, and intentionallly did not extend the abstract typescript codegen.
@TiFu to chime in

[lwj5]

@macjohnny it might seem so, but there are so many components that are reusable from AbstractTypeScriptClientCodegen that are exact duplicates.

By extending It, we remove over 500+ lines of duplicate code (see code changes) and also gain future bug fixes (since the abstract class is used by so many generators). I don't think it defeats the purpose of the unification but instead aids it, nonetheless, any of these methods can be overridden if needed.

Would be nice if we could get @TiFu update if he's going forward on this

[TiFu]

Totally fine for me :)

Given the additional work that has gone into the AbstractTSClientCodegen, let's use it. The rewrite anyway re-used a lot of what AbstractTSClientCodegen was back then, so no harm in continuing to use it and reduce the maintenance effort.