CTConfig: session based auth

[DumbergerL]

Handle diffrent logged in users as session. Enable switching between these sessions, to use the diffrent ct permissons of the users

[DumbergerL]

Requirement in ChurchTools Forum: https://forum.church.tools/topic/9358/churchtools-api-client-php/25?_=1687938612048

[DumbergerL]

Idea for Implementation:

// default session
CTConfig::setApiUrl(...);
CTConfig::authWithCredentials(...);

$myself = PersonRequest::whoami();

// create new session
CTSession::switchSession("person_a_session");

CTConfig::setApiUrl(...);
CTConfig::authWithCredentials(...);

$myselfPersonA = PersonRequest::whoami();

$this->assertNotEquals($myself->getId(), $myselfPersonA->getId());

// switch back to default session
CTSession::switchSession("default");

// get sessions
$sessions = CTSession::getSessions();
// => ["default", "person_a_session"];