Introduce Exclude Fragments option

Allows you to exclude any fragments that get added. 
Good use case: do not deploy litecoin lightning node when using btc lightning

Should also help users with advanced customization scenarios

build.ps1

@@ -21,6 +21,7 @@ docker run -v "$(Get-Location)\Generated:/app/Generated" `
            -e "BTCPAYGEN_CRYPTO9=$BTCPAYGEN_CRYPTO9" `
            -e "BTCPAYGEN_REVERSEPROXY=$BTCPAYGEN_REVERSEPROXY" `
            -e "BTCPAYGEN_ADDITIONAL_FRAGMENTS=$BTCPAYGEN_ADDITIONAL_FRAGMENTS" `
+           -e "BTCPAYGEN_EXCLUDE_FRAGMENTS=$BTCPAYGEN_EXCLUDE_FRAGMENTS" `
            -e "BTCPAYGEN_LIGHTNING=$BTCPAYGEN_LIGHTNING" `
            -e "BTCPAYGEN_SUBNAME=$BTCPAYGEN_SUBNAME" `
            --rm $BTCPAYGEN_DOCKER_IMAGE