Add skeleton commands

[crazywhalecc]

What does this PR do?

Add ext-skel, lib-skel and source-skel command, to help newcomer and maintainer add extension or library more elegant.

Feature:

• [X] Prompt integration
• [X] Generate basic extension and library class
• [X] Generate unix autoconf example
• [X] Generate unix CMake example
• [ ] Generate windows CMake example
• [ ] Generate windows sln example
• [ ] Add config to existing file
• [ ] Support vendor mode
• [ ] Support phar mode

Usage:

# skeleton for extension foo
bin/spc dev:ext-skel foo

# skeleton for library bar
bin/spc dev:lib-skel bar

# skeleton for source baz
bin/spc dev:source-skel baz

Checklist before merging

• [X] If you modified *.php, run composer cs-fix at local machine.
• [ ] If you changed the behavior of static-php-cli, update docs in ./docs/.