`bicep build` service

For portal deployment with bicep files, we need to stand up APIs for sending bicep code and returning the generated template.

Opening this issue specifically for the build service, as the decompile service is being delivered, this issue builds on https://github.com/Azure/bicep/issues/3003

Now that `decompile` is being completed, what scenarios need `build` support?

Start by reading the linked issue 3003 and the decompile-service work referenced in this issue, then review the portal deployment scenario. The work is complete when the required build scenarios are agreed and the API requirements for accepting Bicep code and returning the generated template are defined.

Written by the indexing model from the issue text.