LT-22607 TonePars use XAmpleParser code for result processing

[AndyBlack]

Now that the TonePars utility is part of FLEx, we can have it use the same code that XAmple does when processing its result.

1. This change took the result processing of XAmpleParser and put it in a new public method.
2. ToneParsInvoker now gets an instance of XAmpleParser (or creates it, if needed).
3. The change removes the duplicated code from ToneParsInvoker.
4. ToneParsFLExForm passes in an instance of XAmpleParser.

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This change is 

[github-actions]

NUnit Tests

    1 files  ±0      1 suites  ±0   11m 0s ⏱️ +37s
4 302 tests ±0  4 229 ✅ ±0  73 💤 ±0  0 ❌ ±0 
4 311 runs  ±0  4 238 ✅ ±0  73 💤 ±0  0 ❌ ±0 

Results for commit 0d94b9f. ± Comparison against base commit 6a73c08.

♻️ This comment has been updated with latest results.

[johnml1135]

Claude - Sonnet 5 — automated code review.

Two additional findings sit on lines outside this PR's diff hunks (pre-existing code untouched here), so they can't be attached as inline comments — noting them here instead:

1. Reuse (Src/Utilities/pcpatrflex/ToneParsFLExDll/ToneParsInvoker.cs ~line 101): ConvertNameToUseAnsiCharacters is a byte-for-byte duplicate of XAmpleParser.ConvertNameToUseAnsiCharacters, explicitly commented as "borrowed from SIL.FieldWorks.WordWorks.Parser (ParserCore.dll)". Since this PR already dedupes ProcessParseResults against the same class, and ToneParsInvoker now holds a live XAmpleParser reference, this is a natural candidate to dedupe too (note: XAmpleParser's version is internal static, so calling through would need an accessibility change).
2. Cleanup (Src/Utilities/pcpatrflex/ToneParsFLExDll/ToneParsInvoker.cs line 22): using System.Xml.Linq; is now dead — it was the only consumer's (XElement/Descendants) namespace, and that code was deleted by this PR. No remaining use of any System.Xml.Linq type in the file.