Add query for undelegating time

[mattverse]

Description

This PR adds synthetic_locks field to query SuperfluidUndelegationsByDelegator , as front end needs information on when the lock that is unlocking would be ending.

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For contributor use:

• Targeted PR against correct branch (see CONTRIBUTING.md)
• Updated relevant documentation (docs/) or specification (x/<module>/spec/)
• Added a relevant changelog entry to the Unreleased section in CHANGELOG.md
• Re-reviewed Files changed in the Github PR explorer

[codecov-commenter]

Codecov Report

Merging #988 (7bad078) into main (e10e67e) will decrease coverage by 0.00%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##             main     #988      +/-   ##
==========================================
- Coverage   20.60%   20.60%   -0.01%     
==========================================
  Files         193      193              
  Lines       25232    25234       +2     
==========================================
  Hits         5200     5200              
- Misses      19080    19082       +2     
  Partials      952      952              

Impacted Files	Coverage Δ
x/superfluid/keeper/grpc_query.go	46.55% <0.00%> (-0.55%)	⬇️

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