Generic OIDC provider support

[offtherailz]

In draft waiting for fixes on geostore side, and to update doc in this PR too:

• Requires: OIDC provider geostore#330
• Requires: [FIXES #2408] Refresh Token and Logout OIDC requests geostore#354
• logout URL
• document logout URL
• refresh token

Description

This PR configures the integration of a generic OIDC provider (provided by geosolutions-it/geostore#330 ) in MapStore, documenting it.

Please check if the PR fulfills these requirements

• The commit message follows our guidelines: https://github.com/geosolutions-it/MapStore2/blob/master/CONTRIBUTING.md
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

What kind of change does this PR introduce? (check one with "x", remove the others)

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Other... Please describe:

Issue

#10151

What is the new behavior?

#10151 integrated (logout still to be impelmented on GeoStore, so not closing it).

Breaking change

Does this PR introduce a breaking change? (check one with "x", remove the other)

• Yes, and I documented them in migration notes
• No

Other useful information

[offtherailz]

@tdipisa this is ready to review now.
This should be tested with Azure @afabiani

[tdipisa]

@offtherailz as discussed, I would like to add an entry point section in the documentation to provide an overall picture of available capabilities of the current OpenID support in MS across different OpenID clients / configuration methodologies we have (using old clients and the new one) such as:

• Available clients and what they can do
• Which limits they have
• How them can be combined to provide multiple auths
• Future steps also in term of deprecation of the old clients

I would like to provide only a brief preliminary indication of the above to allow readers to learn the details in the relevant sections of the documentation.

[offtherailz]

This can be merged for me. @tdipisaThe release is confirmed ? review and merge when you want.
If the release is confirmed, I'll proceed with backport.

[tdipisa]

@offtherailz please test with Azure before backporting it. The milestone is confirmed, yes.