Fix default Open action for .url files and add Text Editor support

[AlexAndBear]

Description

Before this fix, clicking "Open" on a .url file in the file-list context menu could result in no action at all.

Root cause: the rendered action was treated as a route link as soon as a route callback existed, even when that callback returned no target. In that case, the handler-backed action ("Open shortcut") was never executed.

What changed:

• In ActionMenuItem, route/href targets are resolved first.
• A route link is rendered only when route(...) returns a concrete target.
• If no route target exists, the action falls back to button behavior and executes the handler.
• .url is now also registered for the Text Editor, so shortcut files can be opened as plain text via "Open with".

Related Issue

• Fixes N/A

How Has This Been Tested?

• test environment: local dev environment (macOS, Node/pnpm workspace)
• test case 1: pnpm --filter @opencloud-eu/web-pkg check:types
• test case 2: pnpm test:unit --run packages/web-pkg/tests/unit/components/ContextActions/ActionMenuItem.spec.ts
• test case 3: pnpm test:unit --run packages/web-app-text-editor/tests/unit/yjs.spec.ts packages/web-app-text-editor/tests/unit/app.spec.ts

Types of changes

• Bugfix
• Enhancement (a change that does not break existing code or deployments)
• Breaking change (a modification that affects current functionality)
• Technical debt (addressing code that needs refactoring or improvements)
• Tests (adding or improving tests)
• Documentation (updates or additions to documentation)
• Maintenance (like dependency updates or tooling adjustments)

[AlexAndBear]

@kulmann this bug has likely been around for quite a while. It appears to have been introduced when we improved the Open / Open with... context-menu actions.
At that time, Open was not shown for .url files in the context menu (see demo).

On current main, Open now appears for .url files (which is good), but we still need to make ActionMenuItem resolve the correct execution path when both handler and route are present.

That combination is an edge case coming from useFileActionsOpenWithDefault, and right now it can lead to Open not executing the expected handler.

Also added text editor support because I just felt like it 😎