docs(sdk): add basic-tests and stores pages

[leandrodamascena]

closes #169

Description of changes:

This PR adds docs/testing-patterns/basic-tests.md documentation for basic test patterns in durable functions.

The guide covers:

• Basic test structure - Simple examples showing how to write tests with the testing framework
• Status checking - Patterns for verifying execution status (SUCCEEDED, FAILED, TIMED_OUT, etc.)
• Result verification - How to assert on function return values
• Operation assertions - Verifying individual operations like steps, waits, and callbacks
• Test organization - Best practices for structuring test files and naming conventions
• Common patterns - Frequently used assertion patterns with clear examples
• Stores

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