Add versioned CHLO ops to VHLO

[GleasonK]

Request description

VHLO (Versioned StableHLO, #278) currently only has versioned ops for StableHLO, but we want to provide stability guarantees for StableHLO and CHLO. Eventually CHLO ops will need to be added to the opset.

[burmako]

The current thinking is that we might not necessarily want to have a spec and compatibility guarantees for CHLO. Instead, we would just decompose CHLO ops into StableHLO ops before serialization. Given that, I'll close this ticket for now until we have a resolution in #602.