For #30066
This adds a new `documentPaste` api proposal that lets extensions hook into copy and paste.
This can be used to do things such as:
- Create link when pasting an image
- Bring along imports when copy and pasting code
* Add experimental support for reading files in data transfer
Adds a new `DataTransfer.asFile` method which lets you get file objects from a `DataTransfer`. This is currently only hooked up for drop into editors.
A few follow ups:
- Right now the file data is also read eagerly when it is transfered to the extension host. Before shipping this we would make this happen lazily instead
- The drop into editor api does not provide a nice way to do anything with the dropped files.
We should at least support returning a `WorkspaceEdit`. However `WorkspaceEdit` only supports text files, so we would also need to add an API that lets it deal with binary files
* Make `asFile` return a value instead of a promise
`asFile().data()` already returns a promise so `asFile` doesn't also need to be async
* Trying resolving data files transfer lazily
* Cleaning up code for lazy drop
* Remove testing code
* Remove unneeded buffer serialize
* 💄
