Give lambda parameters more reasonable names, implement Jit `ourCall`

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 96.66667% with 1 line in your changes missing coverage. Please review.

Project coverage is 78.90%. Comparing base (1e56958) to head (1ba8e70). Report is 1 commits behind head on main.

Files	Patch %	Lines
...ain/java/org/aya/syntax/core/term/call/FnCall.java	0.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1100 +/- ## ============================================ + Coverage 78.87% 78.90% +0.03% - Complexity 3212 3221 +9 ============================================ Files 293 293 Lines 9821 9824 +3 Branches 1161 1163 +2 ============================================ + Hits 7746 7752 +6 + Misses 1428 1425 -3 Partials 647 647 ```

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