Parse SLO endpoint as array from SP metadata

[Zogoo]

The current method for accessing the SLO (Single Logout) endpoint is user-friendly. Because the Service Provider (SP) metadata contains multiple SLO endpoints with different bindings, the Identity Provider (IdP) should respond based on the specified binding.
Therefore, I believe it would be better to enable access using keywords such as "binding."

Current way.

(ruby) sp_config.single_logout_services
{"HTTP-Redirect"=>"http://secfense.example.com/logout"}
(ruby) sp_config.single_logout_services
{"HTTP-Redirect"=>"http://secfense.example.com/logout"}
(ruby) sp_config.single_logout_services.keys
["HTTP-Redirect"]
(ruby) sp_config.single_logout_services.values
["http://secfense.example.com/logout"]

From now

(ruby) sp_config.single_logout_services.first[:binding]

Example:

# IdP initiated SLO request.
If sp_config.single_logout_services.first[:binding] == "HTTP-Redirect"
    redirect_to sp_config.single_logout_services.first[:localtion] + {"SAMLResponse: slo_request}
end

[jphenow]

Similar comment to another PR; this seems like enough of a change to expected APIs that it might warrant putting into a new major version release.

[mjobin-mdsol]

seems like a breaking change. maybe we should first cut a release with a deprecation warning. then bump the version.
I don't now how much this method use used and expected to be a hash...

[Zogoo]

@jphenow, @mjobin-mdsol I have changed the destination to the v0.2.0 branch.
I'm not familiar with maintaining multiple versions of a gem. However, I suggest we leave v0.15.XX as the older version, which only fixes bugs. What do you guys think about it?

[mjobin-mdsol]

@Zogoo

v0.2.0 appears to be below v0.15+
Maybe you meant to be v1.0 and v2.0 but after reviewing those changes again.
I don't have any objection targeting v0.17.0 or cutting v1.0.0 with those changes in.