MODLOGSAML-192: Allow callback endpoint to return RTR tokens when configured

[steveellis]

https://folio-org.atlassian.net/browse/MODLOGSAML-192

• Created this branch from latest release. Plan to merge into a new bx.x branch (to create the CSP release from) and also to master.
• Adds new configuration property useSecureTokens.
• Changes SamlApi route to return RTR tokens when callback:callback and useSecureTokens are present.
• If just callback is present it will work in legacy mode.
• If callback-with-expiry is present for callback config prop it will return RTR tokens.
• Created more json mocks to represent the new requirement of callback AND useSecureTokens.
• Tests are more DRY, creating a few shared methods.
• Pulled in Julian's SimpleSamlPhpContainer class because it helped simplify IdpTest and the new IdpTestCallback. This will make merging easier and is fine since it is just tests.

Hope to get this merged by end of the week to meet the Q CSP 4 deadline.

[sonarcloud]

Quality Gate passed

Issues
21 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[julianladisch]

Looks good, thanks!