Fix multiple mount options not recognized

### What changes are proposed in this pull request?

Fix multiple mount options specified by `-o` not recognized by Alluxio Fuse.
The `-o` option can be specified multiple times, and each time it can take a comma separated list of `key=value` mount options.

### Why are the changes needed?

Fuse mounting with `bin/alluxio-fuse mount hdfs://10.10.1.2:9000/ /work/alluxio_fuse -o kernel_cache -o attr_timeout=6000 -o entry_timeout=6000` errors with

```
Exception in thread "main" com.beust.jcommander.ParameterException: "-o": couldn't convert "kernel_cache,attr_timeout=6000,entry_timeout=6000" to a `key=value` pair because contains more than 1 `=`
	at alluxio.fuse.options.MountCliOptions$KvPairsConverter.convert(MountCliOptions.java:74)
	at alluxio.fuse.options.MountCliOptions$KvPairsConverter.convert(MountCliOptions.java:50)
	at com.beust.jcommander.JCommander.convertValue(JCommander.java:1333)
	at com.beust.jcommander.ParameterDescription.addValue(ParameterDescription.java:249)
```

The bash scripts concatenates the multiple occurrences of `-o` into a comma-separated list and passes it to the Java program. The PR does the other way around, preserving them and splitting the kv pair list in a `-o` option into multiple options.

### Does this PR introduce any user facing changes?

No.

			pr-link: #18026
			change-id: cid-d9b5dcf65ba3de1bd9324ed01f74944171d5ef30

dora/integration/fuse/bin/alluxio-fuse

@@ -186,7 +186,12 @@ launch_fuse_process() {
   while getopts "o:hf" opt > /dev/null 2>&1; do
     case "${opt}" in
       o)
-        mount_options+="${OPTARG},"
+        KV_PAIRS=(${OPTARG//,/ })    # split OPTARG by `,` into array
+        for pair in "${KV_PAIRS[@]}"; do
+          if [[ -n "$pair" ]]; then
+            mount_options+=" -o $pair"
+          fi
+        done
         ;;
       f)
         foreground='true'
@@ -199,19 +204,14 @@ launch_fuse_process() {
         ;;
     esac
   done
+  readonly mount_options
   readonly foreground
-  
+
   if fuse_mounted "${mount_point}"; then
     err "mount: ${mount_point} is already mounted"
     return 1
   fi
 
-  mount_options="$(echo "${mount_options}" | sed -E 's/,*$//g')" # remove trailing comma
-  if [[ -n "${mount_options}" ]]; then
-    mount_options="-o ${mount_options}"
-  fi
-  readonly mount_options
-
   if [[ "${foreground}" == 'true' ]]; then
     ALLUXIO_FUSE_JAVA_OPTS+=" -Dalluxio.logger.type=FUSE_LOGGER,Console"
   fi