Feature: Support Debug mode for SAML provider

[sahya]

Environment

item	version
OS
GROWI	3.6.3
node.js	12.14.0
npm	6.13.4
yarn	1.21.1

(Accessing https://{GROWI_HOST}/admin helps you to fill in above versions)

How to reproduce? (再現手順)

1. no trouble(this is request)

What happens? (症状)

1. no trouble(this is request)

What is the expected result? (期待される動作)

• Debug mode
  • UI: Checkbox or toggle switch (up to you.)
  • Advanced request(if you can); "Debug-log download button" or "Debug-log provide by UI"
• Note: Its profit is a little easy to debugging for admin.
  • I guess that Advanced option may need in case of SaaS because the user may unvisible console.
    • RefernceParam: DEBUG=growi:models:external-account,growi:routes:login-passport,growi:service:PassportService

Related issue

#615: Feature: Support mostly setting items of SAML provider