[editor] Disable "Save" button in query export unless output is filled

When user try to export the query result to HDFS or a new table, without fill in the mandatory input for path or the new table name, the save button should be disabled.

Now for the three options in the dialog, without needed input, we throw different errors. We should improve the UI to prevent user to make mistakes.

1. In HDFS (small csv) : Without giving the file name -->"Save"
[Errno 22] Can not figure out scheme for path ""

2. In HDFS (large file) : Without giving the path-->"Save"
INSERT OVERWRITE DIRECTORY '' select * from queryresulttable limit 3
"Error while compiling statement: FAILED: IllegalArgumentException Can not create a Path from an empty string"

3. A new table : Without giving table name--> "Save"
Server error 500.
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Please see attached screenshots for details.