directdownload: fix keytool importcert

```
$ /usr/bin/keytool -importcert file /etc/cloudstack/agent/CSCERTIFICATE-full -keystore /etc/cloudstack/agent/cloud.jks -alias full -storepass DAWsfkJeeGrmhta6
Illegal option:  file
keytool -importcert [OPTION]...

Imports a certificate or a certificate chain

Options:

 -noprompt               do not prompt
 -trustcacerts           trust certificates from cacerts
 -protected              password through protected mechanism
 -alias <alias>          alias name of the entry to process
 -file <file>            input file name
 -keypass <arg>          key password
 -keystore <keystore>    keystore name
 -cacerts                access the cacerts keystore
 -storepass <arg>        keystore password
 -storetype <type>       keystore type
 -providername <name>    provider name
 -addprovider <name>     add security provider by name (e.g. SunPKCS11)
   [-providerarg <arg>]    configure argument for -addprovider
 -providerclass <class>  add security provider by fully-qualified class name
   [-providerarg <arg>]    configure argument for -providerclass
 -providerpath <list>    provider classpath
 -v                      verbose output

Use "keytool -?, -h, or --help" for this help message
```

Author: weizhouapache

plugins/hypervisors/kvm/src/main/java/com/cloud/hypervisor/kvm/resource/wrapper/LibvirtSetupDirectDownloadCertificateCommandWrapper.java

@@ -86,7 +86,7 @@ private String getKeyStoreFilePath(File agentFile) {
     private void importCertificate(String tempCerFilePath, String keyStoreFile, String certificateName, String privatePassword) {
         s_logger.debug("Importing certificate from temporary file to keystore");
         String keyToolPath = Script.getExecutableAbsolutePath("keytool");
-        int result = Script.executeCommandForExitValue(keyToolPath, "-importcert", "file", tempCerFilePath,
+        int result = Script.executeCommandForExitValue(keyToolPath, "-importcert", "-file", tempCerFilePath,
                 "-keystore", keyStoreFile, "-alias", sanitizeBashCommandArgument(certificateName), "-storepass",
                 privatePassword, "-noprompt");
         if (result != 0) {