fix: reset HTMLEntrypoint state after build (fix #1211)

[jacobq]

I'm not sure if this is "the right solution", but it did seem the most obvious one to me as an outsider, and it does appear to work (fixes #1211). I don't love that it exposes a method (HTMLEntrypoint::initialize) that should probably be private somehow (e.g. calling it after construction but before being "done" may lead to weird/inconsistent states), but I needed a way for the Webpack plugin to reset the HTMLEntrypoint to its pristine/initial state so that it could be reused for subsequent calls to build that used the cached webpack instance (and perhaps a stern warning in a doc comment would be sufficient here...). Open to feedback / alternatives, of course, just wanted to help get this unblocked.

@krisselden I think you made the original PR that refactored the file output to a Webpack plugin. Do you have thoughts on this?

[jacobq]

@ef4 Would you mind approving CI run to make sure I didn't accidentally break any tests? (My local testing only consisted of linking my bug repro app and confirming that it worked correctly with this change though I am running yarn test locally right now in the meantime.)

So far tests are passing though I see some 4.x deprecation warnings like this one:

remove-owner-inject

EPRECATION: As of Ember 4.0.0, owner.inject no longer injects values into resolved instances, and calling the method has been deprecated. Since this method no longer does anything, it is fully safe to remove this injection. As an alternative to this API, you can refactor to explicitly inject `_ajaxRequest` on `adapter`, or look it up directly using the `getOwner` API. [deprecation id: remove-owner-inject] This will be removed in Ember 5.0.0. See https://deprecations.emberjs.com/v4.x#toc_implicit-injections for more details.
        at logDeprecationStackTrace (/tmp/tmp-711579jC8mciX1YtxX/dist/assets/@ember/debug/lib/deprecate.js:112:1)
        at HANDLERS.<computed> (/tmp/tmp-711579jC8mciX1YtxX/dist/assets/@ember/debug/lib/handlers.js:26:1)
        at raiseOnDeprecation (/tmp/tmp-711579jC8mciX1YtxX/dist/assets/@ember/debug/lib/deprecate.js:141:1)
        at HANDLERS.<computed> (/tmp/tmp-711579jC8mciX1YtxX/dist/assets/@ember/debug/lib/handlers.js:26:1)
        at invoke (/tmp/tmp-711579jC8mciX1YtxX/dist/assets/@ember/debug/lib/handlers.js:38:1)
        at deprecate (/tmp/tmp-711579jC8mciX1YtxX/dist/assets/@ember/debug/lib/deprecate.js:187:1)
        at Registry.injection (/tmp/tmp-711579jC8mciX1YtxX/dist/assets/@ember/-internals/container/index.js:828:1)
        at App.inject (/tmp/tmp-711579jC8mciX1YtxX/dist/assets/@ember/-internals/runtime/lib/mixins/registry_proxy.js:223:1)
        at Object.initialize (webpack://app-template/./initializers/ajax.js?:41:17)
        at /tmp/tmp-711579jC8mciX1YtxX/dist/assets/@ember/engine/index.js:128:1
        at Vertices.each (/tmp/tmp-711579jC8mciX1YtxX/dist/assets/dag-map.js:231:1)
        at Vertices.walk (/tmp/tmp-711579jC8mciX1YtxX/dist/assets/dag-map.js:145:1)
        at DAG.each (/tmp/tmp-711579jC8mciX1YtxX/dist/assets/dag-map.js:75:1)
        at DAG.topsort (/tmp/tmp-711579jC8mciX1YtxX/dist/assets/dag-map.js:83:1)
        at App._runInitializer (/tmp/tmp-711579jC8mciX1YtxX/dist/assets/@ember/engine/index.js:155:1)
        at App.runInitializers (/tmp/tmp-711579jC8mciX1YtxX/dist/assets/@ember/engine/index.js:126:1)
        at App._bootSync (/tmp/tmp-711579jC8mciX1YtxX/dist/assets/@ember/application/lib/application.js:578:1)
        at App.boot (/tmp/tmp-711579jC8mciX1YtxX/dist/assets/@ember/application/lib/application.js:545:1)
        at EmberApp._visit (/home/user/tmp/embroider/node_modules/fastboot/src/ember-app.js:257:15)
        at processTicksAndRejections (internal/process/task_queues.js:95:5)
        at EmberApp.visit (/home/user/tmp/embroider/node_modules/fastboot/src/ember-app.js:325:7)
        at FastBoot.visit (/home/user/tmp/embroider/node_modules/fastboot/src/index.js:86:18)
        at Object.visit (/home/user/tmp/embroider/tests/scenarios/helpers.ts:39:16)
        at Object.<anonymous> (/home/user/tmp/embroider/tests/scenarios/fastboot-app-test.ts:110:20)

[ef4]

Thanks for taking a look at this.

It's intentional that the HTMLEntrypoint preserves state across builds. The idea is that you don't bother re-parsing an HTML file that hasn't changed. It's only the contents of the placeholders that need to get recreated each build.

I think what's missing is a call to placeholder.clear() right about here.

[ef4]

Superseded by #1219.