internals rewrite: clean up checks and hypothesis functionality

[cosmicBboy]

This PR organizes the checks and hypothesis modules across the core and backend subpackages for overall consistency:

• The pandera.core.{checks, hypotheses} module specifies the public-facing class API for checks and hypotheses. This provides a way for users to access built-in checks/hypotheses with full auto-completion on an IDE. These methods delegate to the builtin_{checks, hypotheses} modules.
• The pandera.backends.base.builtin_{checks, hypotheses} modules implement base function implementations that use multimethod to dispatch the implementation to a specific data framework (e.g. pandera.backends.pandas.builtin_{checks, hypotheses}
• Base function implementations are marked with @{Check, Hypothesis}.register_builtin_check_fn, and framework-specific implementations are marked with @register_builtin_{check, hypothesis}

This PR also cleans up the way SchemaErrors failure cases are handled. Instead of having pandas-specific logic in the SchemaErrors methods:

• The failure_cases_metadata method was introduced in the BaseSchemaBackend class to handle consolidating and summarizing failure cases from across multiple checks.
• Introduce a FailureCaseMetadata namedtuple class to clarify the metadata needed by SchemaErrors.

[codecov]

Codecov Report

Patch coverage: 99.46% and project coverage change: +0.17 🎉

Comparison is base (76ed3f6) 97.23% compared to head (83ad473) 97.41%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1109      +/-   ##
==========================================
+ Coverage   97.23%   97.41%   +0.17%     
==========================================
  Files          63       67       +4     
  Lines        4710     4789      +79     
==========================================
+ Hits         4580     4665      +85     
+ Misses        130      124       -6     

Impacted Files	Coverage Δ
pandera/backends/pandas/array.py	99.07% <ø> (ø)
pandera/core/pandas/__init__.py	100.00% <ø> (ø)
pandera/decorators.py	99.03% <ø> (-0.49%)	⬇️
pandera/extensions.py	0.00% <ø> (ø)
pandera/core/extensions.py	99.01% <97.14%> (+0.50%)	⬆️
pandera/core/checks.py	98.54% <99.04%> (+1.57%)	⬆️
pandera/__init__.py	88.23% <100.00%> (+0.35%)	⬆️
pandera/backends/__init__.py	100.00% <100.00%> (ø)
pandera/backends/base/__init__.py	100.00% <100.00%> (ø)
pandera/backends/base/builtin_checks.py	100.00% <100.00%> (ø)
... and 14 more

... and 3 files with indirect coverage changes

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[cosmicBboy]

this PR is part 2 in the effort to decouple pandas-specific validation logic from the pandera schema specification: #381