Adding NDJSON serialization support

Adding the ability to serialize to an NDJSON format in addition to the existing HDF5 and compact binary formats.

This format is being added make debugging easier and is not meant for scenarios where performance is important.

For a model like the following:

MyRecord: !record
  fields:
    x: int
    y: int

HelloNDJson: !protocol
  sequence:
    anIntStream: !stream
      items: int
    aBoolean: bool
    aString: string
    aComplex: complexdouble
    aDate: date
    aTime: time
    aDateTime: datetime

    aRecord: MyRecord

    anOptionalIntThatIsNotSet: int?
    anOptionalIntThatIsSet: int?

    aVector: int*
    aDynamicArray: int[]
    aFixedArray: int[2,3]

    aMapWithAStringKey: string->int
    aMapWithAnIntKey: int->int

    aUnionWithSimpleRepresentation: [int, bool]
    aUnionRequiringTag: [int, double]

The NDJSON would look like the following:

{"yardl":{"version":1,"schema":{"protocol":{"name":"HelloNDJson","sequence":[{"name":"anIntStream","type":{"stream":{"items":"int32"}}},{"name":"aBoolean","type":"bool"},{"name":"aString","type":"string"},{"name":"aComplex","type":"complexfloat64"},{"name":"aDate","type":"date"},{"name":"aTime","type":"time"},{"name":"aDateTime","type":"datetime"},{"name":"aRecord","type":"Sandbox.MyRecord"},{"name":"anOptionalIntThatIsNotSet","type":[null,"int32"]},{"name":"anOptionalIntThatIsSet","type":[null,"int32"]},{"name":"aVector","type":{"vector":{"items":"int32"}}},{"name":"aDynamicArray","type":{"array":{"items":"int32"}}},{"name":"aFixedArray","type":{"array":{"items":"int32","dimensions":[{"length":2},{"length":3}]}}},{"name":"aMapWithAStringKey","type":{"map":{"keys":"string","values":"int32"}}},{"name":"aMapWithAnIntKey","type":{"map":{"keys":"int32","values":"int32"}}},{"name":"aUnionWithSimpleRepresentation","type":[{"label":"int32","type":"int32"},{"label":"bool","type":"bool"}]},{"name":"aUnionRequiringTag","type":[{"label":"int32","type":"int32"},{"label":"float64","type":"float64"}]}]},"types":[{"name":"MyRecord","fields":[{"name":"x","type":"int32"},{"name":"y","type":"int32"}]}]}}}
{"anIntStream":1}
{"anIntStream":2}
{"anIntStream":3}
{"aBoolean":true}
{"aString":"hello"}
{"aComplex":[1.0,2.0]}
{"aDate":"2023-05-23"}
{"aTime":"10:50:25.777888999"}
{"aDateTime":"2023-05-23T13:22:51.179178520Z"}
{"aRecord":{"x":3,"y":4}}
{"anOptionalIntThatIsNotSet":null}
{"anOptionalIntThatIsSet":1}
{"aVector":[1,2,3]}
{"aDynamicArray":{"shape":[2,3],"data":[1,2,3,4,5,6]}}
{"aFixedArray":[1,2,3,4,5,6]}
{"aMapWithAStringKey":{"one":1}}
{"aMapWithAnIntKey":[[1,1]]}
{"aUnionWithSimpleRepresentation":false}
{"aUnionRequiringTag":{"float64":44.4}}

There are a few other changes in this PR:

https://github.com/HowardHinnant/date becomes a required dependency, even with C++20 because of the need to format and parse dates.
Binary reader/writers now take std::istream/ std::ostreams, instead of "stream-like" objects.

We could consider:

Making codegen for each format (binary, HDF5, NDJSON) opt-in in the _package.yml file.
Implementing std::ostream::operator<< on the generated types for quick debugging, writing data out in the JSON format.

I have not yet updated the documentation. Looking for feedback first.

microsoft / yardl

Adding NDJSON serialization support #56