feat: add XML 1.1 encoding

[jeremylong]

resolves #73

[Copilot]

Pull Request Overview

This PR adds XML 1.1 encoding support to the OWASP Encoder library. The key difference between XML 1.0 and XML 1.1 is that XML 1.1 allows control characters to be represented as character references (e.g., ) rather than being replaced with spaces, making it more permissive for modern applications that need to preserve these characters.

• Introduced a Version enum to distinguish between XML 1.0 and XML 1.1 encoding rules
• Updated the encoding logic to emit hexadecimal character references for restricted control characters in XML 1.1
• Added public API methods forXml11(), forXml11Content(), and forXml11Attribute() for XML 1.1 encoding

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
core/src/main/java/org/owasp/encoder/XMLEncoder.java	Adds Version enum and version-aware encoding logic for control characters; XML 1.1 encodes C0/C1 control characters as &#xNN; instead of replacing them with spaces
core/src/main/java/org/owasp/encoder/Encoders.java	Defines string constants and encoder instances for the three XML 1.1 contexts (general, content, attribute)
core/src/main/java/org/owasp/encoder/Encode.java	Exposes public API methods for XML 1.1 encoding with comprehensive documentation
core/src/test/java/org/owasp/encoder/XML11EncoderTest.java	Provides comprehensive test coverage for XML 1.1 encoding across all modes and character ranges, though contains a bug in hex formatting for dynamic tests

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[Copilot]

Pull Request Overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated no new comments.

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