Add support for other datasinks

[jpraychev]

What would you like to be added:
Support for multiple backends and authorization schemes.

Why is this needed:
Currently, the datasink CR is mostly coupled with Dynatrace as backend or another backend using token authorization with the same auth header (unlikely). If the backend does not support token authentication but cert based one the integration would fail (example BTP cloud logging). As a workaround users could deploy a OTEL collector in-between and push telemetry to various backends but this requires users to create the OTEL collector themselves using cluster admin roles (in case of MCPs)

[dholeshu]

We would also like to be able to use XSUAA authentication with the metrics operator

[christophrj]

see also #142

[maximiliantech]

@jpraychev does the issue #142 already solve your wish here? Or do you seek something different?