refactor: move TSS vote message from crosschain to observer

[lumtis]

Description

• Move the message to observer module
• Rename to MsgVoteTSS
• Add unit tests for the state transition
• Add an additional static check: either failure or success observation

Closes: #1926

[codecov]

Codecov Report

Attention: Patch coverage is 92.98246% with 8 lines in your changes are missing coverage. Please review.

Project coverage is 55.71%. Comparing base (62999f6) to head (15758f7).

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1966      +/-   ##
===========================================
+ Coverage    55.17%   55.71%   +0.53%     
===========================================
  Files          241      242       +1     
  Lines        13537    13554      +17     
===========================================
+ Hits          7469     7551      +82     
+ Misses        5624     5559      -65     
  Partials       444      444              

Files	Coverage Δ
pkg/chains/status.go	100.00% <100.00%> (ø)
x/crosschain/types/authz.go	100.00% <100.00%> (ø)
x/observer/keeper/msg_server_vote_tss.go	100.00% <100.00%> (ø)
x/observer/keeper/utils.go	62.65% <100.00%> (+2.40%)	⬆️
x/observer/types/ballot.go	95.08% <100.00%> (ø)
x/observer/types/message_vote_tss.go	100.00% <100.00%> (ø)
zetaclient/bitcoin/bitcoin_client.go	16.64% <ø> (ø)
zetaclient/evm/evm_client.go	14.89% <ø> (ø)
zetaclient/zetabridge/tx.go	2.65% <0.00%> (ø)

... and 1 file with indirect coverage changes

[kingpinXD]

lftm , left a minor comment