add get-ignored-tests to toolkit.nu

[amtoine]

this PR adds a new get-ignored-tests to the toolkit.nu to list all ignore tests in the repo

example

the current set of ignored tests

#┬───────file───────┬──────────test───────────┬───────────reason────────────
0│tests/sugar/mod.nu│report                   │`nu_plugin_gstat` is required
1│tests/sugar/git.nu│branch-interactive-delete│interactive
2│tests/sugar/git.nu│branch-interactive-switch│interactive
─┴──────────────────┴─────────────────────────┴─────────────────────────────