Add priority field support in authentication flow executions

[gim-]

Allows to declaratively define authentication flow execution and subflow priority in Keycloak 25 onwards.

Additionally I've removed raisePriority/lowerPriority functions as they don't seem to be used anywhere.

Fixes #296

[gim-]

Test run in GitHub actions appears to be flaky.

[berni2288]

Hey, is there anything that blocks this PR from being merged?
If I understood it right, the Github action test is just buggy.

[gim-]

@berni2288 The project is not maintained unfortunately - #964

[ToniA]

@gim- Any chance you could publish your build into Terraform registry?

Just banging my head against the wall with this priority mess...

[oysteinhauan]

Thanks, we need this desperately. As a temporary solution we have done the following:

1. Fork terraform-provider-keycloak repo and fetch this branch from @gim- 's fork.
2. Run make build, or go build -o terraform-provider-keycloak_v5.0.0-priority
3. Place the executable in your plugin-path, e.g. /Users/username/.terraform.d/plugins/registry.terraform.io/mrparkers/keycloak/5.0.0-priority/
4. Create a .terraformrc file with the following content:

provider_installation {
    filesystem_mirror {
        path = "/Users/username/.terraform.d/plugins"
        include = ["registry.terraform.io/mrparkers/keycloak"]
    }
    direct {
        exclude = ["registry.terraform.io/mrparkers/keycloak"]
    }
}

This tells terraform to not fetch mrparkers/keycloak from the registry, but from your local path.

5. Set the provider version in terraform to 5.0.0-priority (or whatever version name you have chosen)
6. Run terraform init -upgrade.

Hope this can help!