Add float opcode handlers

[austnwil]

Description of changes:

• Adds handlers for fixed-width float opcodes (0x6a-0x6d)

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 89.85507% with 7 lines in your changes missing coverage. Please review.
⚠️ Please upload report for BASE (ion11@10d510d). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
...ion/bytecode/bin11/bytearray/OpcodeHandlerTable.kt	0.00%	4 Missing ⚠️
...main/java/com/amazon/ion/bytecode/NumericReader.kt	86.36%	0 Missing and 3 partials ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##             ion11    #1127   +/-   ##
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  Coverage         ?   68.79%           
  Complexity       ?     6060           
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  Files            ?      196           
  Lines            ?    24837           
  Branches         ?     4346           
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  Hits             ?    17087           
  Misses           ?     6424           
  Partials         ?     1326           

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[popematt]

While the overall code looks correct, I'd like to suggest a slightly different factoring that has a cleaner separation of concerns and will make it easier to re-use some of the code.

I'd recommend creating a utility function such as Short.asHalfToFloat(), and then in the opcode handlers, you have something like this:

val floatValue = byteArray.readShort(position).asHalfToFloat()
BytecodeEmitter.emitFloatValue(destination, floatValue)
return 2

Why? This keeps the float conversion logic separated from the concerns of reading from the byte array, and it means that all of our utility functions are focused with a single responsibility. And when we implement bytecode generators for e.g. ByteBuffer or InputStream, we can read an integer value from those, and then re-use the same conversion logic to get the respective float or double values.

[popematt]

It's okay that you've included this change, but don't go out of your way to find things like this that are not directly related to the code you're working on. It's good to keep the PRs focused.

[austnwil]

I'd recommend creating a utility function such as Short.asHalfToFloat(), and then in the opcode handlers, you have something like this:

Good suggestion, definitely more organized this way