fix: support binary and dateTime in JSON

[karaatanassov]

This change adds support for binary and dateTime in JSON.

For binary golang []byte JSON serialization matches the vCenter format. Thus adding the name ot the maps was enough.

For dateTime the format of time.Time Marshaler and Unmarshaler matches vCenter format. The discriminator code required support for custom marshaling logic. In addition the name had to be mapped.

Description

Please include a summary of the change and which issue is fixed. Please also
include relevant motivation and context. List any dependencies that are required
for this change.

Closes: #3127

Type of change

Please mark options that are relevant:

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to
  not work as expected)
• This change requires a documentation update
• Build related change

How Has This Been Tested?

• Unit tests

Checklist:

• My code follows the CONTRIBUTION
  guidelines of
  this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged

[dekp]

Looks good. Thanks.

[karaatanassov]

@akutz I tried addressing your comments. I posted aggregate single commit here.

You can see the change related to your comments in karaatanassov@1233895

I had to switch assertEqual to us the built-in reflect.DeepEqual as that provides good handling of corner cases like nil

[akutz]

Wait on #3136 before merging this