Add default metadata to AviaryValues

[jkirk5]

Desired capability or behavior.

Refactor behavior of AviaryValues to take default metadata, which will avoid the need to set metadata explicitly.

Courtesy of @dlcaldwelljr-ama-inc:

aviary_options = AviaryValues()  # avoid a meta_data kwarg here; AviaryValues uses kwargs like dict uses them
aviary_options.meta_data = MyMetaData  # internal default would be core meta data
aviary_options.set_val(key, val, units)  # default meta data is reference found at self.meta_data
aviary_options.set_val(key, val, units, meta_data=OtherMetaData)  # use explicitly specified meta data

Is your feature request related to a problem? Please describe.

No response

Associated Bug Report

No response

[jkirk5]

I would like to see defaulting of legacy code variable names to None so you don't have to explicitly specify that

[jkirk5]

This needs additional review - setting metadata explicitly is desired for models where the metadata has been extended

[jkirk5]

I am not sure what this issue means anymore. Possibly meaning that you can set metadata when initializing the AviaryValues object? So you don't have to specify it every time you call the various methods?

Thanks to some clarification from DJ I unmangled the codeblock and it makes more sense now. This could be useful for inside AviaryProblem/AviaryGroup to make sure we are using custom metadata everywhere, without needing to specify every time.