Support fetching without the --progress option

Setting the `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__/input-helper.test.ts

@@ -83,6 +83,7 @@ describe('input-helper tests', () => {
     expect(settings.sparseCheckoutConeMode).toBe(true)
     expect(settings.fetchDepth).toBe(1)
     expect(settings.fetchTags).toBe(false)
+    expect(settings.showProgress).toBe(true)
     expect(settings.lfs).toBe(false)
     expect(settings.ref).toBe('refs/heads/some-ref')
     expect(settings.repositoryName).toBe('some-repo')