[usage] Implement markWorkspaceInstanceSessionAsBilled

[laushinka]

Description

Implements setBilledSession and calls it during workspace start.

Related Issue(s)

Depends on #11999 Fixes #11884

How to test

Release Notes

NONE

Documentation

Werft options:

• [x] /werft with-preview

[werft-gitpod-dev-com[bot]]

started the job as gitpod-build-janrie-mark-billed-11884.13 because the annotations in the pull request description changed (with .werft/ from main)

[werft-gitpod-dev-com[bot]]

started the job as gitpod-build-janrie-mark-billed-11884.19 because the annotations in the pull request description changed (with .werft/ from main)

[laushinka]

@andrew-farries Let me know if anything else is needed to close this one before you leave tomorrow 🙏🏽 I left the GetBilled method because I think it's fine to leave it as a placeholder, but have no strong feelings.

[sagor999]

/hold to unblock merge queue