x/ibc: Implement Timeout Timestamp

[colin-axner]

Closes: #5836

Description

The timestamp represents the nanoseconds elapsed from initial unix time (Jan 1, 1970).

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[lgtm-com]

This pull request introduces 1 alert when merging e2e4878 into fe163e8 - view on LGTM.com

new alerts:

• 1 for Useless assignment to local variable

[colin-axner]

I need to add a default timeout timestamp in addition to the default timeout height in 20-transfers/keeper/keeper.go. Any suggestions?

Edit: Because of the variance in block time per chain, I think I'll just set it to 0, making the timeout be dependent upon the timeout height

[colin-axner]

Also, should timestamp be in Unix nanoseconds or seconds? I initially started using nanoseconds, but I just noticed halt time on the SDK is in Unix seconds. Don't think there are strong arguments for one or the other, but might be best to be consistent despite the separation between ibc and sdk app

[codecov]

Codecov Report

Merging #6022 into master will increase coverage by 0.01%.
The diff coverage is 61.29%.

@@            Coverage Diff             @@
##           master    #6022      +/-   ##
==========================================
+ Coverage   54.64%   54.66%   +0.01%     
==========================================
  Files         425      425              
  Lines       25822    25866      +44     
==========================================
+ Hits        14111    14139      +28     
- Misses      10737    10750      +13     
- Partials      974      977       +3     

[colin-axner]

What is the change log work flow? Do I need to do update anything?

[AdityaSripal]

LGTM 👍

[fedekunze]

LGTM, minor suggestions

[cwgoes]

This looks fine to me, thanks @colin-axner.

At some point, it might be nice to add an option to 20-transfer in the CLI to send using a timestamp timeout instead of a block height timeout.