Add support for boost configs in workstations configs

[modular-magician]

fixes: b/315040685

This change updates google_workstations_workstation_config with the host.gceInstance.boostConfig field that is supported by the cloud workstations api and can be set when creating and updating workstation configs to provide workstations with a configuration that can be boosted up to.

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• Searched through the issue tracker for an open issue that this either resolves or contributes to, commented on it to claim it, and written "fixes {url}" or "part of {url}" in this PR description. If there were no relevant open issues, I opened one and commented that I would like to work on it (not necessary for very small changes).
• Ensured that all new fields I added that can be set by a user appear in at least one example (for generated resources) or third_party test (for handwritten resources or update tests).
• Generated Terraform providers, and ran make test and make lint in the generated providers to ensure it passes unit and linter tests.
• Ran relevant acceptance tests using my own Google Cloud project and credentials (If the acceptance tests do not yet pass or you are unable to run them, please let your reviewer know).
• Read the Release Notes Guide before writing my release note below.

Release Note Template for Downstream PRs (will be copied)

workstations: added `host.gceInstance.boostConfig` to `google_workstations_workstation_config` (beta)

Derived from GoogleCloudPlatform/magic-modules#10176