Add experimental print setting action. The command is of the form:
print account_name listing.index_style
account_name is currently ignored.
The path, e.g. listing.index_style is split by "." and fed to
DotAddressable lookup trait method. The method checks the first segment
in the path if it matches any of the struct's fields, and then calls the
field's lookup method.
Merge ui crate with root crate.
In preparation for uploading `meli` as a separate crate on crates.io.
Workspace crates will need to be published as well and having a separate
`ui` crate and binary perhaps doesn't make sense anymore.