replace controllers with handlers

[arhimede]

Feature Request

Q	A
New Feature	yes
RFC	yes/no
BC Break	yes/no

Summary

[alexmerlin]

@arhimede @MarioRadu @pinclau

Here's a first draft of the Handler refactoring:

---

Account register route:

$app->post('/account/register', AccountHandler::class, 'account.register');

has been replaced with:

$app->post('/user/account', PostUserAccountResourceHandler::class, 'user::create-account');

---

Routes:

$app->post('/account/recover-identity', AccountRecoveryHandler::class, 'account.recover-identity');
$app->patch('/account/activate/{hash}', AccountActivateHandler::class, 'account.activate');
$app->post('/account/activate', AccountActivateHandler::class, 'account.activate.request');
$app->patch('/user/' . $uuid . '/activate', UserActivateHandler::class, 'user.activate');

are not included in the above table because I have not yet decided how to refactor them.
Being that it does not follow any of the usual REST URL patterns (/resource, /resource/{uuid}/subresource, /resource/subresource), I do not have yet a final version for them.

---

Security routes:

$app->post('/security/generate-token', [ErrorResponseMiddleware::class, TokenEndpointHandler::class], 'security.generate-token');
$app->post('/security/refresh-token', [ErrorResponseMiddleware::class, TokenEndpointHandler::class], 'security.refresh-token');

have been replaced with:

$app->post('/security/token', [ErrorResponseMiddleware::class, TokenEndpointHandler::class], 'security::token');

This one route being able to handle both of the previous routes.
Based on the request body, it is able to determine if the intent is to generate/refresh an access token.
Unless someone has an argument on why we should rename it, ErrorResponseMiddleware will keep its name (but it was moved from the App module to the new Security module).
TokenEndpointHandler is part of mezzio/mezzio-authentication-oauth2 so it will not be renamed.

---

Route:

$app->post('/error-report', PostErrorReportResourceHandler::class, 'app::create-error-report');

could also be moved to its own module, ErrorReport.

[arhimede]

Verb               POST 
Resource           UserAccountRecoverIdentity
Type               Resource
Handler            Handler


==========
HandlerPath
Route path 
Route name    user.recover-identity```

[alexmerlin]

Implemented in #385