Allow proxy and tile legal information support

[Waguramu]

Goal: allow users to:

• configure proxy when using erdblick
• access legal information (per map) if it is set on any loaded tiles

Scope:

• Angular app and WASM sources

Deliverables:

• erdblick is using relative paths for http calls (necessary for proxy support)
• legal information for tiles is propagated from mapget to MapService

How to test:

1. Build as usual.
2. Serve with Island 1.
3. Configure a basic proxy as follows:

server {
    listen 80;
    server_name <your-server-name>;
    
    location /<your-sub-path>/ {
        proxy_pass http://127.0.0.1:8089/;
        
        proxy_http_version 1.1;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "upgrade";
        
        # Replace absolute paths in HTML/JS responses
        sub_filter_types text/html;
        sub_filter 'src="/' 'src="/<your-sub-path>/';
        sub_filter 'href="/' 'href="/<your-sub-path>/';
        sub_filter_once off;
    }
    
    # Handle absolute path requests by forwarding them to the app path
    location / {
        rewrite ^/bundle/(.*) /<your-sub-path>/bundle/$1 last;
        rewrite ^/config.json /<your-sub-path>/config.json last;
        rewrite ^/favicon.ico /<your-sub-path>/favicon.ico last;
        return 404;
    }
}

4. Examine tiles' legal information if present by clicking the link in the bottom right corner (only shown if there is any legal information).