This commit renames "Message templates" to "Notification templates"
in the user interface as it suggests that these templates cannot
be used to template anything other than the message. However, message
templates are much more general and can be used to template other fields
too such as the subject of an email, or the title of a Slack message.
* Generate API for writing templates
* Persist templates app logic layer
* Validate templates
* Extract logic, make set and delete methods
* Drop post route for templates
* Fix response details, wire up remainder of API
* Authorize routes
* Mirror some existing tests on new APIs
* Generate mock for prov store
* Wire up prov store mock, add tests using it
* Cover cases for both storage paths
* Add happy path tests and fix bugs if file contains no template section
* Normalize template content with define statement
* Tests for deletion
* Fix linter error
* Move provenance field to DTO
* empty commit
* ID to name
* Fix in auth too
* Template service
* Add GET routes and implement them
* Generate mock for persist layer
* Unit tests for reading templates
* Set up composition root and get integration tests working
* Fix prealloc issue
* Extract setup boilerplate
* Update AuthorizationTest
* Rebase and resolve
* Fix linter error
