refactor: avoid string interpolation

[peter-jerry-ye]

For the abort message, we avoid using string interpolation, as they will introduce the StringBuilder APIs, and the Show APIs. We also use SourceLoc::repr directly instead of using SourceLoc::to_string. Overall this should reduce the size around abort.

This should fix the #3325 better with the following statistics:

=== Raw JS output ===
  abort: 811 bytes (4 functions)
  panic: 550 bytes (2 functions)

=== Minified (esbuild --bundle --minify) ===
  abort: 299 bytes
  panic: 136 bytes
  diff:  +163 bytes (119x overhead)

=== Gzipped ===
  abort: 241 bytes
  panic: 145 bytes
  diff:  +96 bytes

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[coveralls]

Pull Request Test Coverage Report for Build 3529

Details

• 38 of 47 (80.85%) changed or added relevant lines in 7 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.05%) to 95.537%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
builtin/intrinsics.mbt	10	11	90.91%
builtin/utils.mbt	21	29	72.41%

Totals
Change from base Build 3527:	-0.05%
Covered Lines:	14193
Relevant Lines:	14856

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💛 - Coveralls

[hackwaly]

String concat is O(n^2) compared to StringBuilder's O(n).