[typescript-angular] Add encoder configuration, fix default encoder

[cubidobusinesssolutions]

• Add encoder to configuration
• Fix import indention
• Default encoder workaround for common/http: HttpParams encoding of form data angular/angular#18261

PR checklist

• Read the contribution guidelines.
• Ran the shell script under ./bin/ to update Petstore sample so that CIs can verify the change. (For instance, only need to run ./bin/{LANG}-petstore.sh, ./bin/openapi3/{LANG}-petstore.sh if updating the {LANG} (e.g. php, ruby, python, etc) code generator or {LANG} client's mustache templates). Windows batch files can be found in .\bin\windows\. If contributing template-only or documentation-only changes which will change sample output, be sure to build the project first.
• Filed the PR against the correct branch: master, 4.1.x, 5.0.x. Default: master.
• Copied the technical committee to review the pull request if your PR is targeting a particular programming language.

Description of the PR

(details of the change, additional tests that have been done, reference to the issue for tracking, etc)

fixes #3372

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[macjohnny]

cc @TiFu (2017/07) @taxpon (2017/07) @sebastianhaas (2017/07) @kenisteward (2017/07) @Vrolijkx (2017/09) @macjohnny (2018/01) @nicokoenig (2018/09) @topce (2018/10) @akehir (2019/07)

[macjohnny]

Thanks for your PR! I think this is a very helpful configuration option.
I suggest to move the decision logic to the constructor.

[macjohnny]

LGTM

[macjohnny]

@cubidobusinesssolutions can you please re-generate the samples?

Ran the shell script under ./bin/ to update Petstore sample so that CIs can verify the change. (For instance, only need to run ./bin/{LANG}-petstore.sh, ./bin/openapi3/{LANG}-petstore.sh if updating the {LANG} (e.g. php, ruby, python, etc) code generator or {LANG} client's mustache templates). Windows batch files can be found in .\bin\windows. If contributing template-only or documentation-only changes which will change sample output, be sure to build the project first.

[akehir]

Very nice, thanks !

[cubidobusinesssolutions]

@macjohnny

can you please re-generate the samples?

I was hoping I would not have to install Java JRE, Java SDK, and Maven. See additional commits.

[macjohnny]

the remaining CI failure is unrelated

[wing328]

@cubidobusinesssolutions thanks for the PR, which has been included in the 4.1.0 release: https://twitter.com/oas_generator/status/1160000504455319553