Fixes needed in case "example" is in a subdirectory of the web path

there are several small fixes in the example directory in order to have all working:
- all absolute paths should be replaced by relative paths (eg "/login" => "./login")
- in file "views/smart-button.php" the extraProviders.entityName should be "testenv" and not "Testenv"

Here are the fixes I made:

## .htaccess
* spid.php is my temporary replacement to produce the response to the ajax request of my project
* logo/*.svg are the graphics of the IdP

`RewriteCond %{REQUEST_FILENAME} !index.php`
`RewriteCond %{REQUEST_FILENAME} !spid.php`
`RewriteCond %{REQUEST_FILENAME} !.*.svg`
`RewriteRule ^(.+)$ index.php/$1 [QSA,L]`

## index.php
changing the switch as in

`switch (basename($request_uri[0])) {`

and removing the initial slash from the cases.

## views/spid-smart-button/spid-button.min.js
the function "providers()" returns only 8 official providers, missing the 9th (lepida), as well as not providing the correct entityID (sielte).

## Cookie Same Site Policy
There seems to be an issue with the same-site policy: I had to add

`ini_set('session.cookie_samesite', 'None');`

before any call to session_start() to have successfull logins

Hope this can be helpful