Add Meta Package Manager.

[kdeldycke]

Meta Package Manager provides the mpm CLI, a wrapper around all package managers.

Features:

• Inventory and list all package managers available on the system.
• Supports macOS, Linux and Windows.
• List installed packages.
• Search for packages.
• Install a package.
• Remove a package.
• List outdated packages.
• Sync local package infos.
• Upgrade all outdated packages.
• Backup list of installed packages to TOML file.
• Restore/install list of packages from TOML files.
• Pin-point commands to a subset of package managers (include/exclude selectors).
• Support plain, versionned and purl package specifiers.
• Export output to JSON or print user-friendly tables.
• Shell auto-completion for Bash, Zsh and Fish.