feat: Optional application/runtime/otlp input

[k15r]

Description

Changes proposed in this pull request (what was done and why):

• optional ApplicationInput in v1alpha1
• optional RuntineImput for v1beta1
• add optional OTLPInput

Criteria

• Have a new OTLP input available on the dev release only
• The new input can only be activated if there is an OTLP output
• The new input can be used in parallel with runtime input
• The new input can be used without runtime input, making the runtime input optional when used with OTLP output

Changes refer to particular issues, PRs or documents:

• New OTLP input for LogPipeline #1523

Traceability

• The PR is linked to a GitHub issue.
• The follow-up issues (if any) are linked in the Related Issues section.
• If the change is user-facing, the documentation has been adjusted.
• If a CRD is changed, the corresponding Busola ConfigMap has been adjusted.
• The feature is unit-tested.
• The feature is e2e-tested.