Feature request: Rework new-element creation flow

[akphi]

We should rework our current fairly rudimentary interface for creating new elements.

Context and Motivation

Implementation Plan

• Show the full path of the element in the name box (almost like IntelliJ when you create a new element)
• Beautify the element creation modal - refer to new project modal in IntelliJ

• Clicking the plus + button in project explorer will open up the modal, where the right-clicking will not
• CONSIDER Adding multi/nested context-menu for new element, change + to open modal to create new element instead
• CONSIDER We can explore the design from VS Code dropdown in Settings that shows more information about the currently focused item in the dropdown, or Gmail when hovering on each Inbox folder

[akphi]

Also consider the following refactor at code-level

• Restrict the usage of type classifier and consider using the element instead the only mechanism that really needs the type classifier is element creation, which we could refactor to have a plugin that produces a single configuration for the creation ceremony: e.g. type ElementCreatorConfiguration = { key: string; label: string; icon: React.ReactNode; ... }
• Reorganize elements in the dropdown to create new elements: core elemtns goes first, but should be sorted alphabetically, extensions go later and sorted alphabetically as well
• Remove ModelClassifierUtils