fix: normalization error on nested relationship

[kiaking]

A model with more than 2 related models related to the same model was causing a normalization error. It was due to the Schema class was caching the first created schema with its key.

For example, the first relation creates a schema and say its name is proposal_settings. Now the parent of this model is proposal_templates, because it's defined first in Opportunity model.

Next, if the proposals model also depends on proposal_settings, but because the schema for proposal_settings is already created by proposal_templates, it uses the same proposal_settings schema. Now we have problem because the parent model this time should be proposals but it's using the previous proposal_templates.

We've fixed this by caching the schema with model AND parent entity name. So only when the model and the parent name match, we use the cache.

Type of PR:

• Bugfix
• Feature
• Refactor
• Code style update
• Build-related changes
• Test
• Documentation
• Other, please describe:

Breaking changes:

• No
• Yes

[codecov]

Codecov Report

Merging #61 (f0e41a9) into master (c319b3a) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master       #61   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           36        36           
  Lines          834       834           
  Branches       134       134           
=========================================
  Hits           834       834           

Impacted Files	Coverage Δ
src/schema/Schema.ts	100.00% <100.00%> (ø)

---

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 c319b3a...f0e41a9. Read the comment docs.