feat: add --header support to web_check()

quickget

@@ -1298,9 +1298,19 @@ function web_redirect() {
 
 # checks if a URL is reachable
 function web_check() {
+    local HEADERS=()
     local URL=""
     URL=$(web_redirect "${1}")
-    curl --silent --location --head --output /dev/null --fail "${URL}"
+    # Process any headers
+    while (( "$#" )); do
+        if [ "${1}" == "--header" ]; then
+            HEADERS+=("${1}" "${2}")
+            shift 2
+        else
+            shift
+        fi
+    done
+    curl --silent --location --head --output /dev/null --fail "${HEADERS[@]}" "${URL}"
 }
 
 function zsync_get() {