PM-4628: preload edit-project billing accounts

[jmgasper]

What was broken

• Edit Project only exposed a name-search autocomplete with no initial billing-account options, so users could not see the billing accounts they were allowed to select.

Root cause

• The new work app never loaded the project-scoped /projects/:projectId/billingAccounts source used by the legacy flow.
• The autocomplete always started with defaultOptions=false, so the menu opened empty until a 3-character search.

What was changed

• Added a project-scoped billing-account fetch in the work app projects service.
• Preloaded those accounts into the edit-project billing-account autocomplete when a project id is available.
• Passed the current project id from the project editor form into the autocomplete.

Any added/updated tests

• Added a service test for project billing-account normalization.
• Added a FormBillingAccountAutocomplete regression test covering edit-project preload behavior.

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