fix(dialogs/spawnDialog)!: support vue-devtool but lose appContext

[ShGKme]

☑️ Resolves

• Doing small changes from: [RFC] Improve spawnDialog or add a new function #6731
• Allows debugging dialog content with vue-devtools
• Also, getCurrentInstance only works when the dialog is spawned in the setup context, so doesn't even work in a click handler

This looses appContext.

Workarounds:

• Always use locally imported components
• When possible - provide data via props
• For provide/inject - provide directly from the root dialog component
• For Pinia - should work via activePinia, or via provide in the root dialog component

Alternative:

• Pass app/appContext via options and then do hacks - re-provide every provider

🏁 Checklist

• ⛑️ Tests are included or are not applicable
• 📘 Component documentation has been extended, updated or is not applicable
• 2️⃣ Backport bugfixes to stable8 for maintained Vue 2 version.

[susnux]

makes sense and is cleaner, but quite some negative aspects for just some DX.

[ShGKme]

makes sense and is cleaner, but quite some negative aspects for just some DX.

I tried many options and found no way to have both app context and independent rendering.

We can either hack with re-registering all global component, re-providing everything from providers.

Or manually add vnode to the parent's children on beforeUpdate + update (IF there is a parent, and it's not mounted outside Vue apps).

[ShGKme]

And as far as I know, there is no case where we need it at the moment.

[susnux]

We can either hack with re-registering all global component, re-providing everything from providers.

I think this is quite complex solution for a rare condition (when there is even one). So yes lets stick with this PR.

[Antreesy]

LGTM. Let's see how it works in app, when we get to it