Feature/server packages v2 (#574)

* new api models

* use new PackageResource

* do not error out on missing default exports (esmodules auto-execute)

* do not check for js extensions (they might have been registered on the client without a js file)

* prepend the api baseurl to any relataive server JS dependencies

* ignore tsbuildinfo

* create base file for tsconfig

* extend from base config and optimise include/exclude paths

* install rollup plugin to handle json files

* use plugin to bundle json files

* call script for cms builds that builds libs

* add rollup config to utils lib

* add a context token to the extension registry instance itself and provide it through BackofficeElement

* add rollup node resolve

* add node resolve

* only include element mixin in element library

* add error description to module load error

* add types to UmbExtensionRegistry token

* set UmbNotificationService as string in its token to avoid minification

* correct comment

* reverse order of checks

* add host to server extensions and support life-cycle check

* add imports

* use lit rather than lit-html

* correct comment

* add PackageManifestModel

* add import

* run libs build for cms

* revert reorder

* use string name for NotificationContext token

* make alias public readonly of UmbContextToken

* remove TODO

* use UmbContextToken::toString() for all stores

* use string alias for contexts

* move default data so we avoid importing a big lit library just to get default data interface

* add rollup to two extra libraries

* make sure we build uui and lit into our libraries for the few cases we import something

* add lockfile

* add separate options for .js files

* add function to install types of module

* add types output

* remove unused tsconfig-base file for now

src/Umbraco.Web.UI.Client/libs/extensions-api/has-init-export.function.ts

@@ -0,0 +1,8 @@
+import type { UmbEntrypointModule } from "./umb-lifecycle.interface";
+
+/**
+ * Validate if an ESModule exports a known init function called 'onInit'
+ */
+export function hasInitExport(obj: unknown): obj is Pick<UmbEntrypointModule, 'onInit'> {
+	return obj !== null && typeof obj === 'object' && 'onInit' in obj;
+}