Adds multi-file actions in details views

- Enables multi-selection context menu actions in commit and graph details views
- Adds batch support for staging, unstaging, discarding, stashing, and copying paths of multiple files
- Combines file operations atomically to prevent git index lock contention
- Introduces robust unit tests to verify discard and conflict resolution utility logic

Closes #5328

Author: eamodio

CHANGELOG.md

@@ -30,6 +30,7 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/) and this p
 - Adds the ability to reword a commit's message from the _Commit Graph_ — right-click a commit on the current branch and choose _Reword Commit_ ([#5161](https://github.com/gitkraken/vscode-gitlens/issues/5161))
 - Adds a _Modify Commits (Interactive Rebase)_ action to the _Commit Graph_ that opens the interactive rebase editor scoped from the selected commit(s) for squashing, rewording, reordering, dropping, and editing ([#5161](https://github.com/gitkraken/vscode-gitlens/issues/5161))
 - Adds a _Publish Branch_ action to the _Commit Graph_ header that appears when the current branch has no upstream — publishes (pushes and sets the upstream of) the current branch in one click, sitting just left of _Fetch_ and collapsing to its icon when the header is too narrow ([#5327](https://github.com/gitkraken/vscode-gitlens/issues/5327))
+- Adds the ability to multi-select files in the _Commit Graph_ details and _Inspect_ view to act on several at once — Ctrl/Cmd+click to toggle, Shift+click for a range, and Ctrl/Cmd+A to select all — with batch actions from the context menu and toolbar: open files, open selected changes (multi-diff), open on remote, copy paths and relative paths, and (for working changes) stage, unstage, stash, and discard ([#5328](https://github.com/gitkraken/vscode-gitlens/issues/5328))
 
 ### Changed