[New] Add support for NVM_AUTH_HEADER env var

nvm.sh

@@ -117,11 +117,17 @@ nvm_get_latest() {
 
 nvm_download() {
   local CURL_COMPRESSED_FLAG
+  local AUTH_HEADER_FLAG
+
+  if [ -n "$NVM_AUTH_HEADER" ]; then
+    AUTH_HEADER_FLAG="--header $NVM_AUTH_HEADER"
+  fi
+
   if nvm_has "curl"; then
     if nvm_curl_use_compression; then
       CURL_COMPRESSED_FLAG="--compressed"
     fi
-    curl --fail ${CURL_COMPRESSED_FLAG:-} -q "$@"
+    curl --fail ${CURL_COMPRESSED_FLAG:-} ${AUTH_HEADER_FLAG:-} -q "$@"
   elif nvm_has "wget"; then
     # Emulate curl with wget
     ARGS=$(nvm_echo "$@" | command sed -e 's/--progress-bar /--progress=bar /' \
@@ -133,6 +139,10 @@ nvm_download() {
                             -e 's/-sS /-nv /' \
                             -e 's/-o /-O /' \
                             -e 's/-C - /-c /')
+
+    if [ -n "$AUTH_HEADER_FLAG" ]; then
+      ARGS="$AUTH_HEADER_FLAG $ARGS"
+    fi
     # shellcheck disable=SC2086
     eval wget $ARGS
   fi