Add Support for Request parameters

[weyCC81]

Is there a simple option on the client or resource to give nested values back?

Comparison with "pysnow"
There were the following parameters in pysnow available

client.parameters.display_value = False
client.parameters.exclude_reference_link = True

Implementation in "aiosnow"
I found an option to call the display value for nested objects, but it looks like there is a lot of code needed to implement that.
What options are available to define some specific values of a table to be display values?

Workaround 01 / #27 #97

<StringMapping [key=1da4392, value=Company)]>

Usage of ModelSchema with json_normalize = partly solved (is that the way to go?)

Workaround 02 / #91

<IntegerMapping [key=7, value=Closed]>

Usage of fields definition = partly solved (just key not value)
https://github.com/rbw/aiosnow/blob/ae362b9238461d1823f1fc3564578832c899ea04/docs/usage/model/declare.rst

Solution

fields.String(pluck=Pluck.DISPLAY_VALUE)

Is it possible to enable Pluck on a global scale?

Reference:

• https://pysnow.readthedocs.io/en/latest/usage/parameters.html
• Conversion to dataframe, options around "Display_Value" pysnow#188
• https://github.com/rbw/aiosnow/tree/ae362b9238461d1823f1fc3564578832c899ea04/examples