Have rebar3.cmd work on a Windows CMD shell (#151)

* Provide a working rebar.cmd for system that need it

(Windows on non-PowerShell)

* Add tests for recent changes

If the "run" were to fail the job would too

* Check if Rust can find it

.github/workflows/windows.yml

@@ -70,6 +70,17 @@ jobs:
         if: ${{matrix.combo.gleam-version}}
       - name: rebar3 version (action)
         run: echo "rebar3 ${{steps.setup-beam.outputs.rebar3-version}}"
+      - name: Run rebar3 and rebar3.cmd
+        run: |
+          # Should not fail
+          rebar3 version
+          rebar3.cmd version
+        if: ${{matrix.combo.rebar3-version}}
+      - name: rebar3 from Rust
+        run: |
+          cd test-projects/rust_rebar3_cmd
+          cargo test -- --nocapture
+        if: ${{matrix.combo.rebar3-version}}
       - name: mix version and help (CLI)
         run: |
           mix -v