Move solo machine sequence to client state

[colin-axner]

Description

We want to remove height references from the ConsensusState interface and implementations since the height is already being used as the value when looking up consensus states. This is sub pr in achieving that goal.

It moves the sequence to the client state.

ref: #7176

---

Before we can merge this PR, please make sure that all the following items have been
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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 #7271 into master will decrease coverage by 0.42%.
The diff coverage is 49.74%.

@@            Coverage Diff             @@
##           master    #7271      +/-   ##
==========================================
- Coverage   55.60%   55.17%   -0.43%     
==========================================
  Files         457      584     +127     
  Lines       27440    40536   +13096     
==========================================
+ Hits        15257    22365    +7108     
- Misses      11083    16301    +5218     
- Partials     1100     1870     +770     

[cwgoes]

utACK, seems straightforward.