Pass the consumer instance to error and response handlers

[prkumar]

The @error_handler and @response_handler decorators registers callbacks for users to perform specific follow-up operations on success and error cases.

In this PR, both decorators now support the optional argument requires_consumer. When this option is set to True, the registered callback should accept a reference to the Consumer
instance as its leading argument:

@error_handler(requires_consumer=True)
def raise_api_error(consumer, exc_type, exc_val, exc_tb):
     """Wraps client error with custom API error"""
        ...

class GitHub(Consumer):
    @raise_api_error
    @post("user/repo")
    def create_repo(self, name: Field):
        """Create a new repository."""

This adds value to other features, like #117.

[codecov]

Codecov Report

Merging #118 into master will not change coverage.
The diff coverage is 100%.

@@          Coverage Diff          @@
##           master   #118   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files          25     25           
  Lines        1405   1419   +14     
  Branches      131    134    +3     
=====================================
+ Hits         1405   1419   +14

Impacted Files	Coverage Δ
uplink/builder.py	100% <100%> (ø)	⬆️
uplink/decorators.py	100% <100%> (ø)	⬆️
uplink/session.py	100% <100%> (ø)	⬆️
uplink/hooks.py	100% <100%> (ø)	⬆️

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