[typescript-rxjs] Add RxJS 7 support

[jopelle1]

This PR adds support for RxJS 7.
Related PR : #9958

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  ./bin/utils/export_docs_generators.sh
  

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@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)

[macjohnny]

@jopelle1 can you change the target branch to 5.4? So we could include it in the next minor release

[jopelle1]

@jopelle1 can you change the target branch to 5.4? So we could include it in the next minor release
@macjohnny Done !

[macjohnny]

And please also rebase to the master branch, otherwise we get a huge list of changes

[jopelle1]

And please also rebase to the master branch, otherwise we get a huge list of changes

Done !

[macjohnny]

@jopelle1 closing this in favor of #9958, since the next release will be 6.0.0, so we can have a breaking change. thanks for your effort!