[Bug]: file names with leading - are interpreted as program options

[229c9cf0]

Describe the bug

File names starting with a dash - (a.k.a. hyphen-minus) are interpreted as program options unless a double-dash -- is used to separate them from file names. Currently, it seems file names are simply appended without this separator.

Whenever an explicit file list is passed to git, this leads to a failure of that invocation. (E.g. when manually staging a file by clicking the + next to it in the source view.) Instead, the git usage message is returned as a red notification bubble.

While I don't see any obvious exploits resulting from this, I haven't bothered to dig deeper. It's probably a good idea to fix this soon.

Relevant errors (if available)

error: unknown switch `((some part of the filename))'
usage: git add [<options>] [--] <pathspec>...

    -n, --dry-run         dry run
[...]

Steps to reproduce

1. Create a file with a hyphen at the start of its name, e.g. -INBOX- (names like that are useful because they sort to the very top)
2. Open the plugin's Source Control View
3. Click the + next to the file under "Changes" to stage the changes.

Expected Behavior

The file should be staged normally.

Addition context

This should be quite easy to fix by adding -- into all template strings in front of the place where file names are appended / interpolated.

Operating system

Windows