TBI - Improve consistency and documentation of authentication handling across middlewares and tasks

[tobiasqueck]

Description (include screenshots)

While being at UI5Con, I have noticed that our documentation about how we handle authentication across the tools has room for improvements. On the one hand, it is not clearly documented and on the other hand, there are subtle differences between the middlewares that need to be aligned.

Value

A clear documentation helps consumers to better utilize the tools, and a consistent behavior is the expectation of consumers.

Architecture Elaboration

n/a

Notes

Tasks

• [x] Add handling of Fiori tools CI/CD variables to the system-access module to be consistent with the backend-proxy-middleware
• [ ] Evaluate using system-access in the backend-proxy-middleware
• [ ] Enhance the READMEs of system-access and all its consumers to clearly explain how authentication is handled
• [ ] Enhance the README of the @sap/ux-ui5-tooling module with at least references to the inclued open source module readmes for further information

[marianfoo]

I want to add that the debug parameter in the deploy tasks is documented neither in help.sap nor in the readme. It's in the readme for the deploy task itself which was linked in the console after I experienced a error.

Also in the help.sap there is a tip to use DEBUG=ux-odata-client npm run deploy. Does that work?
https://help.sap.com/docs/SAP_FIORI_tools/17d50220bcd848aa854c9c182d65b699/1b7a3be8d99c45aead90528ef472af37.html?locale=en-US&q=Debug