[python-muranoclient] importing package by FQPN

In order to further support cataloguing of packages on external resources we need to allow importing packages by FQPN. The actual package location should be composed from the package name (possibly version) and a base URL supplied to the CLI tools via ENV variable or CLI option. A change to murano cli command `package-import` should allow it to distinguish between a file, a url and a FQPN to choose the source location of the package.