Test: added unit tests for Number component

[imayuss]

Short description of the fix

Added unit tests for the Number component covering rendering with default & custom props.

• Added number.test.tsx following the conventions in block.test.tsx.
• Covered default rendering integer/ decimal/ negative/ zero/ large number formatting, minDecimalDigits/ maxDecimalDigits rounding & padding behavior fixDecimalDigits overriding both the tooltip & wholeLengthNumberInTooltip props.
• Covered custom style merging & a smoke test across darkMode/ colorScheme combinations.
• Included one optional snapshot test.

Files changed: tests/ui/basic-components/number.test.tsx

Issue to close #67

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• Synced repo before changes?
• Documentation updated (if needed)?
• Functionality verified locally?