Fix variable name from string catalog with an acronym in the name

[liamnichols]

If a Strings Catalog contained an uppercase acronym at the start, the variable name generated would incorrectly only lowercase the first character.

For example:

URLStrings.xcstrings would generate a struct called URLStrings as expected, but the variable/label would be uRLStrings which is not expected.

In this PR, I update the logic so that we lowercase the n-1 initial characters if more than 1 character is uppercased at the start of the string.

This means that the example above will generate a variable named urlStrings

[github-actions]

✅ Pull Request passed benchmark checks

Summary

Sun Oct 13 15:11:21 UTC 2024

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Threshold deviations for XCStringsToolBenchmarks:StringGenerator.generateSource(for:tableName:accessLevel:)
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Time (total CPU) (ms, Δ)	main	pull_request	Difference Δ	Threshold Δ
p0	289	292	2	0
p25	290	292	2	0
p50	290	292	2	0

New baseline 'pull_request' is WORSE than the 'main' baseline thresholds.

---

Comparing results between 'main' and 'pull_request'

Host 'Mac-1728830263551.local' with 3 'arm64' processors with 7 GB memory, running:
Darwin Kernel Version 23.6.0: Wed Jul 31 20:50:13 PDT 2024; root:xnu-10063.141.1.700.5~1/RELEASE_ARM64_VMAPPLE

XCStringsToolBenchmarks

StringGenerator.generateSource(for:tableName:accessLevel:) metrics

Time (total CPU) (ms) *	p0	p25	p50	p75	p90	p99	p100	Samples
main	289	290	290	293	302	302	302	4
pull_request	292	292	292	292	293	293	293	4
Δ	3	2	2	-1	-9	-9	-9	0
Improvement %	-1	-1	-1	0	3	3	3	0