[WIP] Make multiple classes and types internal for encapsulation

[Copilot]

Thanks for assigning this issue to me. I'm starting to work on it and will keep this PR's description up to date as I form a plan and make progress.

Original prompt

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This section details on the original issue you should resolve

<issue_title>The project exposes a large number of implementation types that should be hidden from consumers</issue_title>
<issue_description>- [ ] Make Jq.Parse internal

• Change JqFilter to internal abstract class; make CreateNullElementStatic, StructurallyEqual, GetTypeNameStatic, GetValueTextStatic internal
• Change JqParser to internal sealed class
• Change JqHaltException to internal sealed class
• Change JqBreakException to internal sealed class
• Change JqEnvironment to internal sealed class
• Change JqPattern, VariablePattern, ArrayPattern, ObjectPattern to internal
• Change FilterClosure to internal sealed record
• Change BinaryOp to internal enum
• Change UserFunctionDef to internal sealed class
• Change all ~30 filter classes in Filters/ to internal sealed class
• Update tests that use Jq.Parse to use Jq.Evaluate
• Build and verify

Comments on the Issue (you are @copilot in this section)

• Fixes The project exposes a large number of implementation types that should be hidden from consumers #6

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