New UI for inserting date macros/placeholders/keystroke emulations

[GaurangTandon]

1. A simple toolbar at the bottom of the snippet body editor (not attached to the quill editor, since we want the new toolbar to be available to both plain and rich text).
2. Having options to easily insert a date/time macro, date/time arithmetic, placeholders, and keystroke emulations.
3. Pushing either of the above would launch a popup where user can compose desired macro/placeholder/keystroke emulation with ease.

First step: (Gaurang) Implement a mockup of the popup Second step: (Varun) do your magic and make the UI of the popup beautiful :)

More: this UI paves way for linking embedding existing snippet into another snippet, and pushing in websitre urls (just like clipboard pastes)

[iWrote]

explain in person later, not sure i follow

i do kind of get it

[iWrote]

bump in-person