Cover webhook authentication modes

[dantro86]

Summary

• cover GitHub SHA-256, generic HMAC-SHA256, generic HMAC-SHA512, Bitbucket SHA-256, and Basic webhook authentication
• verify invalid authentication does not start a task and valid authentication executes the integration template
• send the exact JSON bytes used to calculate signatures
• redact webhook signatures and authorization headers from HTTP diagnostics and Allure step parameters
• update the API coverage map

Verification

• qualityGate
• core-sqlite-local WebhookIntegrationApiTest: 8/8 passed
• verified against Semaphore develop at 232bfb242b1eeda93717098d46283a7582279f0a
• inspected generated Allure JSON and HTTP attachments to confirm authentication values are redacted