Fixes https://github.com/ohmyzsh/ohmyzsh/commit/140c977a3d82410f48c198596de193d2d6b7b9b5#commitcomment-73688165

Fixes #10884
Closes #10910

Fixes #10884

BREAKING CHANGE: the boot2docker project was abandoned in 2020,
so it makes no sense to keep the plugin. If you were using it,
remove it from the `$plugins` array.

Fixes #10877

Fixes #10878

Since `set -e` is enabled, when `commit.gpgsign` is not set the
`git config` command would show an error. Given that it is technically
not ignored, the subshell would exit.

With this change, the `commit.gpgsign` setting is properly tested
by doing the fallback test if the command fails, so no exit status
code ends up quiting the subshell.

Co-authored-by: inclusive-coding-bot <inclusive-coding-bot@github.com>

Co-authored-by: Marc Cornellà <hello@mcornella.com>

This change still supports CLI 1, but shows a deprecation warning
on the first run of `opswd`. Support for CLI 1 shall be removed
in the near future.

Closes #10787
Co-authored-by: Marc Cornellà <hello@mcornella.com>

Co-authored-by: Mohan Sha <mohansha@outlook.com>