"Copy Prompt" icons on files

[andrewpareles]

We'd like to add icons in the sidebar that let you quickly copy file and folder contents to the clipboard.

For files:

• Add an icon that, when clicked, copies a file's name and content to the clipboard. For example, clicking the button on tsconfig.json would copy this:

tsconfig.json:
```json
{
"extends": "./tsconfig.base.json",
"compilerOptions": {
	"types": [],
	"plugins": []
},
```

For folders:

• Icon to copy hierarchy. For example, copying folder1 would give this hierarchy:

folder1
   - file1.json
   - file2.ts
   - folder2
      - file3.ts

• Icon to copy hierarchy and all files together, concatenated.

[[hierarchy]]
[[file1]]
[[file2]]
...