CommitSig Timestamp can be zero time

[greg-szabo]

Go implementation
In CommitSig, in the BlockIDFlagAbsent type, the Timestamp field is a Go "Zero value" (0001-01-01T00:00:00Z).

ADR-025
The Timestamp field in Absent signatures should be null or omitted.

Current Rust implemenation
Rust implemented the ADR.

Problem
Tendermint-Rust is incompatible with Tendermint-Go.

Solution

• done #277 Add a compatibility code to the Rust implementation.
• [todo] Add an issue to the Go repository
• [todo] Remove the compatibility code when the Go code adheres to ADR-025

Relevant discussion:
#196 (comment)

[greg-szabo]

Next step: open a Go issue and link it here. (I need to reproduce the issue in Go for them.)

[liamsi]

This was resolved in #277

I think we should rather close this PR. If the changes are made in go (and there will be potenially more substantial changes in the light of tendermint/tendermint#4857). As this will be breaking on the gos ide too this will bubble up again. Let's open an issue when it becomes relevant again.

Feel free to re-open this issue if you think we should open an issue in amino or tendermint and link it here.