Reduce allocations for formatting exception stack traces

[HaloFour]

Reduces the number of allocations when formatting exception stack traces.

1. Accepts a CharSequence instead of a String so that an underlying StringBuilder can be passed directly without requiring an intermediate allocation.
2. Reimplements EcsJsonSerializer#formatStackTraceAsArray to use Matcher to iterate over the CharSequence to avoid allocating the ArrayList<String>, String[] and each individual String element.

[apmmachine]

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• Start Time: 2022-04-26T14:42:05.193+0000

• Duration: 8 min 40 sec

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Test	Results
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Passed	198
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Total	198

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[eyalkoren]

Thanks for this PR!
Please see HaloFour#1 which proposes some further allocation reduction.

[HaloFour]

Thanks for the assist! 😃