NewManager returns a new plugin manager.

Checksum contains the hash function and the checksum we expect from a plugin.

Command represents each item defined in the `commands` key of the `plugin.toml` file.

ExistError indicates that a plugin installation failed because it's already installed.

InstallOpts are installation options for plugin resources.

Manager retrieves the plugins available for the current cluster by navigating into the filesystem.

Plugin is the structure representation of a `plugin.toml file.