[spiral/core] Parent scopes in the `has` method

[msmakouz]

Q	A
Bugfix?	✔️
Breaks BC?	❌
New feature?	❌

Before these changes, the has method of the container did not check for the existence of a binding in parent scopes. This has been fixed.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (3f18fd9) 89.50% compared to head (f28bdd3) 89.51%.

:exclamation: Current head f28bdd3 differs from pull request most recent head 82390c7. Consider uploading reports for the commit 82390c7 to get more accurate results

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #1065 +/- ## ========================================= Coverage 89.50% 89.51% - Complexity 6316 6318 +2 ========================================= Files 824 824 Lines 17797 17801 +4 ========================================= + Hits 15930 15934 +4 Misses 1867 1867 ```

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