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:

• Prompt integration
• Generate basic extension and library class
• Generate unix autoconf example
• 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

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