refactor: remove new APIs on x/token

[0Tech]

Motivation and context

As this module is obsolete, we do not plan to add any more new features.
Security maintenance may continue.

Checklist:

• I followed the contributing guidelines and code of conduct.
• I have added a relevant changelog to CHANGELOG.md
• I have added tests to cover my changes.
• I have updated the documentation accordingly.
• I have updated API documentation client/docs/swagger-ui/swagger.yaml

[codecov]

Codecov Report

Merging #609 (d7f1a8f) into main (8b9e3e5) will increase coverage by 0.19%.
The diff coverage is 97.46%.

@@            Coverage Diff             @@
##             main     #609      +/-   ##
==========================================
+ Coverage   59.56%   59.76%   +0.19%     
==========================================
  Files         811      811              
  Lines       95263    94491     -772     
==========================================
- Hits        56744    56472     -272     
+ Misses      34974    34563     -411     
+ Partials     3545     3456      -89     

Impacted Files	Coverage Δ
x/collection/codec.go	0.00% <0.00%> (ø)
x/collection/collection.go	78.57% <0.00%> (-2.92%)	⬇️
x/collection/keeper/msg_server.go	74.85% <ø> (+0.92%)	⬆️
x/collection/msgs.go	41.29% <ø> (+9.90%)	⬆️
x/token/codec.go	0.00% <ø> (ø)
x/token/keeper/msg_server.go	68.99% <ø> (-0.57%)	⬇️
x/token/msgs.go	30.45% <ø> (+0.34%)	⬆️
x/collection/keeper/grpc_query.go	89.58% <80.76%> (-3.13%)	⬇️
x/collection/client/testutil/query.go	100.00% <100.00%> (ø)
x/collection/client/testutil/suite.go	99.60% <100.00%> (+<0.01%)	⬆️
... and 17 more