Update bytecode and add test utilities

[popematt]

Issue #, if available:

None

Description of changes:

• Fixes the Bytecode debug rendering so that there isn't a trailing (space) after instructions with no packed data.
• Adds test utility methods for converting strings of hexadecimal octets into ByteArray
• Adds assertion and helper method for checking the equality of bytecode.
• Adds an IMPORT instruction to the bytecode
• Adds more documentation about the content of the directive instructions
• Adds more doc comments to BytecodeGenerator

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov]

Codecov Report

❌ Patch coverage is 50.00000% with 4 lines in your changes missing coverage. Please review.
⚠️ Please upload report for BASE (ion11@45f34fc). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
...c/main/java/com/amazon/ion/bytecode/ir/Debugger.kt	50.00%	2 Missing and 1 partial ⚠️
...in/java/com/amazon/ion/bytecode/ir/Instructions.kt	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##             ion11    #1111   +/-   ##
========================================
  Coverage         ?   68.07%           
  Complexity       ?     5711           
========================================
  Files            ?      180           
  Lines            ?    23821           
  Branches         ?     4230           
========================================
  Hits             ?    16217           
  Misses           ?     6303           
  Partials         ?     1301           

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[austnwil]

Looks good! Thanks again for those convenience methods

[tgregg]

Should these be contained in s-expressions?

[popematt]

The S-Expressions are for human readability more than anything else. If you think that we should keep the S-Expressions in the bytecode, we can, but it's not strictly necessary to make things work.

[tgregg]

Got it, let's keep the bytecode as lean as possible.