feat: Make server port configurable via a property in app.properties

[mattp-swirldslabs]

As an engineer running a Block Node I want to be able to configure the port for the Block Node So that I can run the server on a different port

Tech Notes

• This property is currently exposed in BlockNodeApp.start():

 // Build the web server
        // TODO: make port server a configurable value.
        final WebServer webServer = webServerBuilder
                .port(8080)
                .addProtocol(pbjConfig)
                .addRouting(pbjRouting)
                .addRouting(httpRouting)
                .build();

• We already have an established pattern for ingesting parameters found in app.properties in the Server.java class. This feature should follow the existing pattern.
• The property will need to be sanity checked as a positive integer with a min value of 1 and a reasonable max port value
• The current default 8080
• The property might be named server.port

[AlfredoG87]

according to IANA, the well-known ports are from 0 to 1023 so the min value should be 1024 and a max of 65,535 that is the maximun allowable port number due to the 16 bits restriction.