Fix dependency resolution when branch name contains ']' character (#2313)

### ❔What, Why & How

Branch names can legally contain a `]` character (git forbids `[` but
allows `]`), for example a mangled `[master]` tag left over as
`master]`. When such a branch's build-project dependencies are
downloaded, the artifact folder name embeds that `]`. In
`GetDependencies` (the `thisBuild` path in `Github-Helper.psm1`), the
already-resolved dependency folder was enumerated with `Get-ChildItem
-Path $folder`. `-Path` treats `]` as a wildcard metacharacter, so
instead of listing the `.app` files inside the folder it returned the
folder itself as a single match. That folder path was then added to the
downloaded-apps list and "published" as if it were an app, resulting in
0 apps actually installed (`Installing apps took 0 seconds`) and
downstream failures.

The fix uses `-LiteralPath` instead of `-Path`. `$folder` comes from
`Get-Item $downloadName` and is already a fully resolved directory path,
so there is never a reason to re-interpret it as a wildcard. For any
path without `[`/`]` the two are identical, so existing behavior is
unchanged; the only difference is that bracket-containing paths now
enumerate their `.app` files correctly.

Verified against a real failing microsoft/BCApps CI run (the log printed
the folder, not the `.app` files, as "found from previous job") and
reproduced/covered with a regression test.

### ✅ Checklist

- [x] Add tests (E2E, unit tests)
- [x] Update RELEASENOTES.md
- [ ] Update documentation (e.g. for new settings or scenarios)
- [ ] Add telemetry

Co-authored-by: aholstrup1 <aholstrup1@users.noreply.github.com>