This commit fixes how templates were reloaded. There was a bug in
the plugin which used the output of the precompiled templates for
development only dependencies, instead of the templates directory.
This caused the templates to be always compiled and added as a
resource on runtime classpath, when we only wanted the raw templates.
This commit also adds functional tests to the build logic, which
can be executed by running `./gradlew build-logic:test`.
