Added documentation for hybrid testing with IAS

[mariayord]

No description provided.

[chgeo]

@mariayord I have fixed the build issues.

[renejeglinsky]

Hi @mariayord ,
I think the better place for this would be in the new security guide: https://pages.github.tools.sap/cap/docs/guides/security/authentication#hybrid-auth

There you could also spare some of the steps as they are already described: https://pages.github.tools.sap/cap/docs/guides/security/authentication#ias-ready

[mariayord]

Hi @renejeglinsky ,
I already synced with @BraunMatthias , https://pages.github.tools.sap/cap/docs/guides/security/authentication#hybrid-auth is planned for other use case.
I tested Hybrid testing with IAS only for Node.js , the steps for Java are may be the same, but not sure if it works.
As I understand the security guide is for the both runtimes. Please notice we have a guide in the same page also for Hybrid testing with XSUAA.