landingpage: fix svg logos are too big

[MarcelCoding]

[BF] Summary of fix - fixes [inex|islandbridgenetworks]/IXP-Manager#x
Configures a maximum size for the logo on the login page (and other pages) as svg logos are growing infinite in size

In addition to the above, I have:

• ensured all relevant template output is escaped to avoid XSS attached with <?= $t->ee( $data ) ?> or equivalent.
• ensured appropriate checks against user privilege / resources accessed
• API calls (particular for add/edit/delete/toggle) are not implemented with GET and use CSRF tokens to avoid CSRF attacks

BEFORE:

AFTER: