v0.11: Sign in with Microsoft, custom email sending

Highlights

• Microsoft is now available as 3rd-party identity provider. Admins can set up a "Sign in with Microsoft" authentication option for users in the backend config. Both personal and work accounts are supported. Learn more here.
• Custom email sending is now supported by a new webhook and the option to disable email sending through the Hanko backend. Apps can subscribe to the webhook and implement their own email sending (e.g. passcode emails).

What's Changed

• docs: add link to discord guide in backend readme by @lfleischmann in #1424
• feat(thirdparty): add microsoft provider by @lfleischmann in #1409
• Update LICENSE by @FlxMgdnz in #1432
• Update README.md by @FlxMgdnz in #1433
• chore(deps): bump github.com/labstack/echo/v4 from 4.11.4 to 4.12.0 in /backend by @dependabot in #1436
• fix: fix saml login for existing users by @FreddyDevelop in #1434
• [FEAT] disable email delivery by @FreddyDevelop in #1419
• chore(deps): bump golang.org/x/net from 0.21.0 to 0.23.0 in /quickstart by @dependabot in #1440
• chore(deps): bump github.com/labstack/echo-contrib from 0.15.0 to 0.17.1 in /backend by @dependabot in #1441
• fix: don't override error before return by @FreddyDevelop in #1447

Full Changelog: backend/v0.10.2...backend/v0.11.0