Add sumologic_o365_audit_source resource

[vsinghal13]

Description

Add support for O365 Audit Source with App Registration Authentication

Summary

This PR adds a new Terraform resource sumologic_o365_audit_source that enables collection of Office 365 audit logs using Azure AD App Registration authentication.

Changes

New Resource: sumologic_o365_audit_source

• Collects Office 365 audit logs via the Office 365 Management Activity API
• Supports Azure AD App Registration authentication with:
  • tenant_id - Azure AD tenant ID
  • client_id - Azure AD application (client) ID
  • client_secret - Azure AD client secret (marked as sensitive)
• Configurable workload types:
  • Audit.Exchange - Exchange audit logs
  • Audit.AzureActiveDirectory - Azure AD audit logs
  • Audit.SharePoint - SharePoint audit logs
  • Audit.General - General audit logs
  • DLP.All - Data Loss Prevention logs
• Supports Office 365 deployment regions:
  • Commercial - Commercial cloud
  • GCC - Government Community Cloud
  • GCC High - Government Community Cloud High

HTTP Source Enhancements

Extended the HTTPSource struct to support third-party references with new types:

• HTTPThirdPartyRef - Container for third-party resource configurations
• HTTPResource - Resource configuration with service type, path, and authentication
• HTTPPath - Path configuration for O365 notification endpoints
• HTTPAuthentication - Authentication configuration for App Registration

Bug Fix

Fixed base_url provider configuration to properly read from SUMOLOGIC_BASE_URL environment variable at runtime using schema.EnvDefaultFunc instead of os.Getenv().

Testing

• Added comprehensive acceptance tests in resource_sumologic_o365_audit_source_test.go
• Tests verify resource creation, updates, and proper handling of sensitive fields
• Tests read credentials from environment variables:
  • SUMOLOGIC_TEST_O365_TENANT_ID
  • SUMOLOGIC_TEST_O365_CLIENT_ID
  • SUMOLOGIC_TEST_O365_CLIENT_SECRET
• All tests passing ✅

Documentation

Added complete documentation at website/docs/r/o365_audit_source.html.markdown including:

• 4 usage examples covering different workloads and regions
• Prerequisites for Azure AD app registration setup
• Import instructions
• Complete argument and attribute reference

Check list

• Describe the changes and their purpose
• Update HTML docs (if applicable)
  • preview tool
• Update CHANGELOG.md
• Check CONTRIBUTING.md for anything forgotten

[github-actions]

⚠️ Warning: Please update CHANGELOG.md with your changes.

[vsinghal13]

    resource_sumologic_monitors_library_monitor_test.go:522: Step 2/2 error: Error running apply: exit status 1
        
        Error: ***"id":"7Z1J2-9ST0M-2CBV5","errors":[***"code":"permission:invalid_subject","message":"Invalid Subject.","detail":"One or more subjects does NOT exist!"***]***
        
          with sumologic_monitor.test,
          on terraform_plugin_test.tf line 3, in resource "sumologic_monitor" "test":
           3: resource "sumologic_monitor" "test" ***
        
--- FAIL: TestAccSumologicMonitorsLibraryMonitor_update (11.48s)

unrelated test failing cc @ashpaliwal