Follow up work for Patch Item Listing

[gsaslis]

very rough, unprocessed notes follow:

• TODO: maninak check what happens when diffing non-text file like images
• TODO: maninak as first treeItem if an expanded patch show files changed +${A} ~${M} -${D} (colored) and/or total count of lines added/removed
• TODO: maninak show lines added | removed on filechange item tooltip when this is resolved https://radicle.zulipchat.com/#narrow/stream/369277-heartwood/topic/missing.20entry.20for.20deleted.20file.20in.20httpd's.20.2Fdiff.20response
• TODO: maninak show M or A or D (colored!) at the right-most side of each file treeitem signifying modified, added or deleted
• TODO: maninak add checkbox next to each item which on hover shows tooltip "Mark file as viewed". A check should be keyed to each revision.id+file.resolvedPath. Sync state across vscode instances. Add a config to toggle showing it.
• TODO: maninak prefix each Patch item description with ✓ (or put on the far right as icon) if branch is checked out and in tooltip with (✓ Current Branch).
• TODO: maninak open the diff editor using the actual path and in unchangeable read-only (opening a diff of an old commit via the native git plugin shows "Editor is read-only because the file system of the file is read-only." which means we could perhaps have the files in-memory instead of using temp files??! Maybe this is related https://github.com/microsoft/vscode-extension-samples/tree/69333818a412353487f0f445a80a36dcb7b6c2ab/source-control-sample or maybe a URI with custom scheme https://code.visualstudio.com/api/extension-guides/virtual-documents#textdocumentcontentprovider) or by making a Repository https://stackoverflow.com/questions/54952188/showing-differences-from-vs-code-source-control-extension/54986747#54986747
• TODO: maninak show Gravatar or stable randomly generated avatar (use the one from radilce-interface) on Patch list item tooltip. Prefix PR name with status e.g. Draft • or [Draft]. Add a new radicle.patches.icon config with options [Status icon, Gr(avatar), None] https://github.com/microsoft/vscode-pull-request-github/blob/d53cc2e3f22d47cc009a686dc56f1827dda4e897/src/view/treeNodes/pullRequestNode.ts#L315
• TODO: maninak make a new ticket to create a new expandable level of all Revisions inside a Patch and outside the files list. Expanding the Patch should auto-expand the most recent revision. Expanding a revision should collapse all other revisions of a Patch. On right-click there should be an option to "Open Diff since Revision..." and show a list of all revisions of this Patch for the user to select one. On selection open diff with that as base On right-click there should be an option to "Open Changes since Commit..." and show a selection list of all commits on that revisions up until one marked "base". On selection open diff with that as base. If both of the above are implemented, then make a sublist "Open Changes since" with the above as sub-items.