[REQUEST] - methods to validate non positive and non negative numbers

[natanfeitosa]

Is your feature request related to a problem? Please describe.
Methods to validate non-positive and non-negative numbers to make the process more concise and standardized

Describe the solution you'd like

from kohi import NumberSchema

NumberSchema().nonnegative().validate(-1) # False
NumberSchema().nonnegative().validate(0) # True
NumberSchema().nonnegative().throw().validate(-1) # ValidationError: number must be greater than or equal to 0

NumberSchema().nonpositive().validate(1) # False
NumberSchema().nonpositive().validate(0) # True
NumberSchema().nonpositive().throw().validate(1) # ValidationError: number must be less than or equal to 0