fix: keep the key when t from useLingui is used as a shorthand property

[andrii-bodnar]

IdentReplacer only overrode fold_ident, so in { t } the single identifier that serves as both key and value was renamed to $__, producing { $__ }. Expand the shorthand to { t: $__ } instead, matching the Babel macro.

Fixes #278

[codecov]

Codecov Report

❌ Patch coverage is 90.90909% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 94.42%. Comparing base (32bb27a) to head (a10b7f1).

Files with missing lines	Patch %	Lines
crates/lingui_macro/src/lib.rs	90.90%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #281      +/-   ##
==========================================
- Coverage   94.44%   94.42%   -0.02%     
==========================================
  Files          11       11              
  Lines        2518     2529      +11     
==========================================
+ Hits         2378     2388      +10     
- Misses        140      141       +1     

Flag	Coverage Δ
unittests	94.42% <90.90%> (-0.02%)	⬇️

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Files with missing lines	Coverage Δ
crates/lingui_macro/src/lib.rs	91.45% <90.90%> (-0.02%)	⬇️

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