Bitcoin wallets have a sweep all function to transfer all coins from one private key to another. Is there such a feature in a bitcoin lightning wallet where you can sweep all coins from a lightning private key to another lightning address?
There are currently no specifications for interoperable text/file formats between lightning network node implementations. The lightning BOLT specifications deal with standardization of the network protocols so that different lightning implementations can talk to one another, but all other details which are not part of this protocol are left up to the individual client implementers to choose.
It will probably be useful to have a standardized import/export format for lightning node information and channels in future, so that you can migrate your node information to an alternative implementation. I'm not aware of anybody working on such formats to date.
Channels in the Lightning Network are tightly coupled to a specific node with a specific public key. It is not really possible to migrate channels to a node with a different public key, and attempting to do so will likely get both nodes blacklisted, as the specification indicates that blacklisting should occur if any duplicate channel is broadcast with a node id which does not match the one previously known.