* Support Forrest parity testing for F3 participation APIs
For parity testing, Forest nodes need to decode an F3 participation
ticket that is issued by Lotus. Lotus so happens to use CBOR to encode
tickets, which it then decodes to issue a lease.
The lease issuer is of type `peer.ID` which is an alias of type `string`
that may contain non UTF-8 characters. If this type is used directly in
CBOR encoding then it gets encoded as string, which works fine in Golang
but not Rust, which in turn results in decoding issues in Forest.
To avoid this use `[]byte` as the type to encode the issuer public key.
In Lotus, the value will be the binary marshalling of `peer.ID` that
issued the ticket.
While at it, also fix two issues that were brought up during discussion:
* A miner must not be able to ask for a ticket to participate in zero
instances. Validate and return error if instances is set to zero.
* Use CBOR tuple encoding for a slightly better efficient wire encoding
of ticket. `cborgen.Write*` APIs explicitly create a given file; hence
the need to separate the file to which tuple kinds are generated since
the existing encoding for types in `api/cbor_gen.go` use maps.
