Feature: Support Algorithm SHA-256 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)

• Algorithm option selectable
• sha256
  • Digest Algorithm
  • Signature Algorithm
• Note; The SHA-356 Algorithm of SAML is defect standard. The current version uses the SHA-1 algorithm. if you need to change SHA-256, it must be source code.

Related issue

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