Preview: Allows changing the preview environment inside the preview app, and other UX changes that enhance the experience (#20598)

* Preview Device: refactored config

Fixed "flip" icon style.

Removed "shadow" as unnecessary.

Renamed "className" to "wrapperClass" to be descriptive.

* Preview element CSS refinement

* Preview element: load in private extensions

* Added "Preview Environments" preview-app

Made `unique`, `culture` and `segment` observable in the context.

* Aligned preview-app design

with `hidden` attribute and design consistency.

* Created "Preview" package

* Relocated "Preview Apps" and Context to the new package

* Deprecated `UmbDocumentPreviewRepository` (for v19)

as the methods have moved to `UmbPreviewRepository`.

* Removed Preview Sessions event listeners

* Changed localization from "End" to "Exit"

* chore: consumes context only when needed

* feat: uses the UmbPreviewRepository instead

* feat: adds localization to errors and ensures the function does not randomly throw

* feat: prevents creating a new repository for every click

* feat: prevents potential memory leak by adding a signal to the events added to each iframe update

* feat: adds a custom interface to prevent typescript errors

* feat: ensures new string states are checked properly

* docs: adds comment to avoid confusion

* feat: sets up scaling once per iframe load rather than on each update

* fix: ensures that you can go back to the default segment again

* feat: closes popovers when clicking on the iframe (losing blur) and if selecting an item (expect for devices)

---------

Co-authored-by: Jacob Overgaard <752371+iOvergaard@users.noreply.github.com>

src/Umbraco.Web.UI.Client/package-lock.json

@@ -3638,6 +3638,10 @@
 			"resolved": "src/packages/performance-profiling",
 			"link": true
 		},
+		"node_modules/@umbraco-backoffice/preview": {
+			"resolved": "src/packages/preview",
+			"link": true
+		},
 		"node_modules/@umbraco-backoffice/property-editors": {
 			"resolved": "src/packages/property-editors",
 			"link": true
@@ -17084,6 +17088,9 @@
 		"src/packages/performance-profiling": {
 			"name": "@umbraco-backoffice/performance-profiling"
 		},
+		"src/packages/preview": {
+			"name": "@umbraco-backoffice/preview"
+		},
 		"src/packages/property-editors": {
 			"name": "@umbraco-backoffice/property-editors"
 		},