Apply custom_formatters on ANY-typed Schemas

[phrfpeixoto]

Proposed solution for #149

I've also refactored some tests, in addition to writing additional cases for using custom_formatters with objects.

[codecov]

Codecov Report

Merging #150 into master will increase coverage by 0.25%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #150      +/-   ##
==========================================
+ Coverage   96.19%   96.44%   +0.25%     
==========================================
  Files          58       58              
  Lines        1602     1603       +1     
==========================================
+ Hits         1541     1546       +5     
+ Misses         61       57       -4

Impacted Files	Coverage Δ
openapi_core/schema/schemas/exceptions.py	86.44% <ø> (+3.38%)	⬆️
openapi_core/schema/schemas/models.py	97.28% <100%> (+0.61%)	⬆️

---

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[codecov]

Codecov Report

Merging #150 into master will increase coverage by 0.5%.
The diff coverage is 100%.

@@            Coverage Diff            @@
##           master     #150     +/-   ##
=========================================
+ Coverage   96.19%   96.69%   +0.5%     
=========================================
  Files          58       58             
  Lines        1602     1603      +1     
=========================================
+ Hits         1541     1550      +9     
+ Misses         61       53      -8

Impacted Files	Coverage Δ
openapi_core/schema/schemas/exceptions.py	86.44% <ø> (+3.38%)	⬆️
openapi_core/schema/schemas/models.py	97.28% <100%> (+0.61%)	⬆️
openapi_core/compat.py	100% <0%> (+44.44%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 0e30b71...a6694f4. Read the comment docs.

[p1c2u]

Rewritten unmarshalling process handles the case. Hence closing