[Pre async-backing] [Moonbase] Use relay-slot number as clocktime

[Agusrodri]

What does it do?

Replaces the previous parachain block number that was used as a clocktime in parachain staking by the relay chain slot number.

The reason for this is that it is advised to rely on the relay chain slot number instead of the parachain's block number due to the relay slot is more stable and works better together with the future async-backing changes.

Related forum post: https://forum.polkadot.network/t/blocknumber-vs-timestamps-should-we-abandon-blocktimes-altogether/4077/2

TODO

• Refactor migrations

[github-actions]

Coverage Report

@@                     Coverage Diff                     @@
##           master   agustin-relay-clocktime      +/-   ##
===========================================================
- Coverage   80.94%                    80.90%   -0.04%     
  Files         287                       287              
+ Lines       94330                     94465     +135     
===========================================================
+ Hits        76355                     76423      +68     
+ Misses      17975                     18042      +67     

Files Changed	Coverage
/pallets/parachain-staking/src/lib.rs	90.62% (+0.04%)	🔼
/pallets/parachain-staking/src/tests.rs	91.59% (+0.01%)	🔼
/precompiles/parachain-staking/src/mock.rs	97.81% (+0.08%)	🔼
/runtime/common/src/apis.rs	85.38% (+0.10%)	🔼
/runtime/common/src/migrations.rs	67.48% (-23.19%)	🔽
/runtime/moonbase/src/lib.rs	49.75% (+0.71%)	🔼
/runtime/moonbase/tests/common/mod.rs	95.64% (+0.17%)	🔼
/runtime/moonbeam/src/lib.rs	45.80% (-0.13%)	🔽
/runtime/moonriver/src/lib.rs	45.79% (-0.13%)	🔽

Coverage generated Tue Jan 23 14:21:09 UTC 2024

[librelois]

It looks pretty good overall, but we need to understand why a collator now needs a delegation to produce blocks, it's not normal.