x/ibc: ClientState Any

[fedekunze]

Description

closes: #XXXX

---

Before we can merge this PR, please make sure that all the following items have been
checked off. If any of the checklist items are not applicable, please leave them but
write a little note why.

• Targeted PR against correct branch (see CONTRIBUTING.md)
• Linked to Github issue with discussion and accepted design OR link to spec that describes this work.
• Code follows the module structure standards.
• Wrote unit and integration tests
• Updated relevant documentation (docs/) or specification (x/<module>/spec/)
• Added relevant godoc comments.
• Added a relevant changelog entry to the Unreleased section in CHANGELOG.md
• Re-reviewed Files changed in the Github PR explorer
• Review Codecov Report in the comment section below once CI passes

[codecov]

Codecov Report

Merging #6952 into master will decrease coverage by 2.52%.
The diff coverage is 42.10%.

@@            Coverage Diff             @@
##           master    #6952      +/-   ##
==========================================
- Coverage   62.10%   59.57%   -2.53%     
==========================================
  Files         519      368     -151     
  Lines       31990    21664   -10326     
==========================================
- Hits        19866    12907    -6959     
+ Misses      10513     7685    -2828     
+ Partials     1611     1072     -539     

[cwgoes]

utACK

[fedekunze]

replaced by #6878