feat: replace store_update_{time,height} by metadata update

[mina86]

Observe that update time and height are always read and manipulated
together. Replace pairs of methods for reading, updating and deleting
time and height with a single combined method for each operation.

Specifically, replace:
a) client_update_{time,height} by client_update_meta,
b) store_update_{time,height} by store_update_meta and
c) delete_update_{time,height} by delete_update_meta.

This allows better optimised implementations which, for example, keep
both pieces of information in a single map and perform a single lookup
to read or update them.

Furthermore, since the host timestamp and height come from the
implementation, remove those arguments from the store_update_meta
method with the implementation fetching the information by itself.

Closes: #973

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PR author checklist:

• Added changelog entry, using unclog.
• Added tests.
• Linked to GitHub issue.
• Updated code comments and documentation (e.g., docs/).
• Tagged one reviewer who will be the one responsible for shepherding this PR.

Reviewer checklist:

• Reviewed Files changed in the GitHub PR explorer.
• Manually tested (in case integration/unit/mock tests are absent).

[codecov]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (45b1c97) 70.23% compared to head (c0127c9) 70.11%.

Files	Patch %	Lines
ibc-clients/ics07-tendermint/src/client_state.rs	83.33%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #981      +/-   ##
==========================================
- Coverage   70.23%   70.11%   -0.12%     
==========================================
  Files         177      177              
  Lines       17733    17676      -57     
==========================================
- Hits        12455    12394      -61     
- Misses       5278     5282       +4     

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