Fix initializing soft button object error states

[joeljfischer]

Fixes #2067

Risk

This PR makes no API changes.

Testing Plan

• I have verified that I have not introduced new warnings in this PR (or explain why below)
• I have run the unit tests with this PR
• I have tested this PR against Core and verified behavior (if applicable, if not applicable, explain why below).

Unit Tests

• Removed unnecessary stubs from soft button object tests

Core Tests

• Tested setting multiple soft buttons, some with one state and some with multiple states

Core version / branch / commit hash / module tested against: Manticore (Core v8.0.0)
HMI name / version / branch / commit hash / module tested against: Manticore (Generic_HMI v0.11.0)

Summary

This PR updates creating SoftButtonObjects to properly crash in DEBUG when states are invalid and return nil in RELEASE.

Changelog

Bug Fixes

• Creating SoftButtonObjects properly crash in DEBUG when states are invalid and return nil in RELEASE.

Tasks Remaining:

n/a

CLA

• I have signed the CLA

[codecov]

Codecov Report

Merging #2068 (bd8041d) into develop (0b534d8) will increase coverage by 0.00%.
The diff coverage is 61.11%.

❗ Current head bd8041d differs from pull request most recent head d14d3dd. Consider uploading reports for the commit d14d3dd to get more accurate results

@@           Coverage Diff            @@
##           develop    #2068   +/-   ##
========================================
  Coverage    85.83%   85.83%           
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  Files          447      447           
  Lines        23377    23392   +15     
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+ Hits         20066    20079   +13     
- Misses        3311     3313    +2