Closes #2281

Summary by cubic

Adds a Jira Service Management connector to index service desk tickets with request type, participants, and SLA status. Registers the source in the backend and web UI; supports full loads and incremental polling with label and size filters. Addresses bounty #2281.

• New Features

  • New JiraServiceManagementConnector scoped to projectType = service_desk.
  • Enriches tickets with request type, participants, and SLA text; skips by labels and enforces a 100KB size limit after enrichment.
  • Supports full and incremental sync; uses jsm_user_email/jsm_api_token; adds DocumentSource.JIRA_SERVICE_MANAGEMENT, registry entry, web source, and basic tests.

• Bug Fixes

  • Enforces post-enrichment size check and applies projectType = service_desk when project_key is set.
  • Sanitizes project keys in JQL and validates empty sanitized keys.
  • Corrects SLA parsing: reads SLA name from top-level, aligns status fields with JSM API, returns empty when no values, uses the friendly remaining time for ongoing cycles, and guards null ongoingCycle.
  • Adds Accept: application/json, explicit HTTP timeouts, and graceful 429 handling; trims skip-label env var; improves logging; fixes docs link; removes BOM; narrows exceptions to RequestException; fixes mutable default for labels_to_skip.

^{Written for commit 43a9b196ae693b94bcc32a6446118997c7cc4610. Summary will update on new commits.}

/claim #2281