Add gridmenu appet

[fredcw]

Maybe this could be the new cinnamon default menu or users could be given a choice at install time between this and the classic list menu as Cinnamon seems to be the only DE without an icon menu by default.

This is basically a slimmed down version of Cinnamenu applet.

Features:

• Home directory file search
• Emoji search
• Drag and drop apps, files, and folders onto the sidebar
• Layout options: sidebar on top, bottom, left, or right of menu. Show/hide sidebar and categories.
• Backward compatible with existing cinnamon themes (no themes need updating)
• Built in file system browser + add directories as menu categories.
• Files and recently used files shown as thumbnails rather than icons + categorised recent files
• Built in simple calculator with JS math functions.
• Fuzzy search

Maybe the name should be changed to icon-menu or app-menu?
Emoji search terms are English only as there are about 2000 emoji with 5-6 search terms each so probably too much to translate.

Here's the settings-override.json file for inclusion in the applet folder for Mint distro only (Mint specific panel icons):
settings-override.json

Here's the menu for testing purposes (including style changes to default theme):
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