Support fetching without the --progress option (#1067)

Setting the `show-progress` option to false in the `with` section of the
workflow step will cause git fetch to run without `--progress`.

The motivation is to be able to suppress the noisy progress status
output which adds many hundreds of "remote: Counting objects: 85%
(386/453)" and similar lines in the workflow log.

This should be sufficient to resolve #894 and its older friends,
though the solution is different to the one proposed there because
it doesn't use the --quiet flag. IIUC git doesn't show the progress
status by default since the output is not a terminal, so that's why
removing the --progress option is all that's needed.

Adding the --quiet flag doesn't make a lot of difference once the
--progress flag is removed, and actually I think using --quiet would
suppress some other more useful output that would be better left
visible.

Signed-off-by: Simon Baird <sbaird@redhat.com>

__test__/git-auth-helper.test.ts

@@ -806,6 +806,7 @@ async function setup(testName: string): Promise<void> {
     sparseCheckoutConeMode: true,
     fetchDepth: 1,
     fetchTags: false,
+    showProgress: true,
     lfs: false,
     submodules: false,
     nestedSubmodules: false,