get Tile Url
Generates the tile URL for the specified tile coordinate.
Replaces placeholders: {z}, {x}, {y}, {s} (subdomain), {apikey}
Subdomain rotation uses (x + y) % 3 to distribute load across subdomains a, b, c.
API keys are retrieved from ApiKeyManager if required.
Return
The complete URL for downloading the tile
Parameters
tile
The tile coordinate