Refactored [Button] tests

[hyochan]

Description

Migrated [Button] tests from react-test-renderer to react-native-testing-library with 100% test coverage.

Tests

Tested [Button] with 100% coverage. Events and conditional rendering with different styles are tested.

Checklist

Before you create this PR confirms that it meets all requirements listed below by checking the relevant checkboxes ([x]). This will ensure a smooth and quick review process.

• [x] I read the Contributor Guide and followed the process outlined there for submitting PRs.
• [x] Run yarn test or yarn test -u if you need to update snapshot.
• [x] Run yarn lint
• [x] I am willing to follow-up on review comments in a timely manner.

[codecov[bot]]

Codecov Report

Merging #375 (6c5869f) into master (1a70802) will increase coverage by 1.19%. The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #375      +/-   ##
==========================================
+ Coverage   72.25%   73.44%   +1.19%     
==========================================
  Files          36       36              
  Lines         919      919              
  Branches      256      256              
==========================================
+ Hits          664      675      +11     
+ Misses        189      188       -1     
+ Partials       66       56      -10