chore: Fix useMobile tests

[jperals]

These tests were failing, but they were not run because the folder name was wrong (_tests__ instead of __tests__).

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.90%. Comparing base (97a9ccb) to head (62122fe).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #191      +/-   ##
==========================================
- Coverage   99.05%   98.90%   -0.16%     
==========================================
  Files          42       44       +2     
  Lines        1165     1185      +20     
  Branches      316      318       +2     
==========================================
+ Hits         1154     1172      +18     
- Misses         10       12       +2     
  Partials        1        1              

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[jperals]

The test code was copied over from the components package, but here it didn't work because the implementation of getIsMobile behaves differenttly in one package vs the other when window.matchMedia is not present:

• In components, we fall back to the getMatchingBreakpoint function: https://github.com/cloudscape-design/components/blob/ea2b35b0ec1e6fd4dfb365542542a480bd75da01/src/internal/hooks/use-mobile/index.ts#L33
• In this package, we use safeMatchMedia which will return false without resorting to fallbacks: https://github.com/cloudscape-design/component-toolkit/blob/main/src/internal/utils/safe-match-media.ts#L7

Fallbacks are not needed because matchMedia has very good browser support: https://developer.mozilla.org/en-US/docs/Web/API/Window/matchMedia#browser_compatibility