Adding new __repr__ for pyspark StructField such that the error logs explicitly show metadata differences

[henrytomsf]

Description

Helps address #76 Added a new class StructFieldPrettyPrint that will allow better representation of the StructFIeld type to show the name, data type, nullability, and the metadata. Currently pyspark's __repr__ attribute (docs) only returns:

return "StructField(%s,%s,%s)" % (self.name, self.dataType,
                                          str(self.nullable).lower())

This is not ideal when users want to compare all the attributes including metadata since it won't show up in the error message.

The new __repr__ in the StructFieldPrettyPrint will override the pyspark StructField's __repr__ method with something more explicit:

return "StructField(%s, %s, %s, %s)" % (
            f"'{self.structfield.name}'",
            self.structfield.dataType,
            str(self.structfield.nullable).lower(),
            str(self.structfield.metadata)
        ) 

Type of change

• New feature (non-breaking change which adds functionality)
• This change requires a documentation update

How has this been tested?

• Passes existing testing suite (pytest tests/)

[henrytomsf]

I'm not sure how you want to handle the image assets that need to be changed for the documentation in the README as I assume there's some styling that we should adhere to so I left that update out.

but I see this now:

E           chispa.schema_comparer.SchemasNotEqualError: 
E           +-------------------------------------------+----------------------------------------------------------------------------+
E           |                  schema1                  |                                  schema2                                   |
E           +-------------------------------------------+----------------------------------------------------------------------------+
E           |    StructField('test_age', LongType(), True, {})    |                    StructField('test_age', LongType(), True, {})                     |
E           | StructField('test_name', StringType(), true, {}) | StructField('test_name', StringType(), true, {'description': 'test description'}) |
E           +-------------------------------------------+----------------------------------------------------------------------------+