shell-deps-check should have a way to ignore specific deps

[Taffer]

For example, if a script has optional capabilities that require a desktop environment or an optional dependency, something like:

    # display, feh, gm, qdbus, qrencode are only necessary when displaying QR
    # codes or copying to a desktop environment's clipboard.
    - uses: test/tw/shell-deps-check
      with:
        files: /usr/bin/pass
        strict: false

could instead be:

    # display, feh, gm, qdbus, qrencode are only necessary when displaying QR
    # codes or copying to a desktop environment's clipboard.
    - uses: test/tw/shell-deps-check
      with:
        files: /usr/bin/pass
        ignore: display feh gm qdbus qrencode

and the output could be:

Dependency Check Results
========================
Analyzed: 1 shell script(s)
Checked against PATH: /usr/bin
Mode: report-only
/usr/bin/pass:
shell: /usr/bin/env bash
dependencies found: 27
 ✓ available (22): cat cp diff dirname find git grep head mkdir mktemp mv pkill rm rmdir sed sleep sort tail tr tree tty which
 - ignored (5): display feh gm qdbus qrencode
 ✗ missing (0):
---
Summary:
Total scripts analyzed: 1
Total dependencies found: 27
Total ignored commands: 5
Total missing commands: 0
Total GNU compatibility issues: 0
✗ Issues found in 0 of 1 file(s)