Handle GPX byte-order marks and XML encodings

[bensynapse]

I run Live Tennis API.

Fixes #190. GPX.read(Path) rejects the supplied UTF-8 BOM file because InputStreamReader turns its encoding marker into prolog text before StAX sees it. Pass byte streams directly to the XML parser through the existing non-closing wrapper, allowing it to consume byte-order marks and honor declared encodings. Use StringReader for fromString so already-decoded text keeps its existing behavior.

Validation on Linux with Temurin 25:

• ./gradlew build --stacktrace --info passes all 1,000 tests and builds the library, source and Javadoc JARs.
• Four encoding regressions fail before the fix and pass afterward. Coverage includes stream/path reads, UTF-8 with/without BOM, UTF-16 in both byte orders, declared Latin-1, decoded strings, and leaving caller-owned streams open on success and failure.
• Both original attachments from GPX.read cannot handle Files with BOM #190 produce identical GPX objects with the built JAR, including all 1,798 track points; the BOM attachment fails on upstream.

[jenetics]

@bensynapse Thank you for the fix.