This closes#2112
Added the ability on problems panel to specify a comma separated list of
tag names to be converted to columns.
If a tag name is present multiple times, it will return the value of all
tags separated with comma.
For optimum readability, the tag names are Capitalized for the visible
column name.
Also, for optimum readability, the custom tags are always placed before
the "Tags" column.
In case a tag is not there for a problem, an empty string is returned.
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Co-authored-by: Jocelyn Collado-Kuri <jcolladokuri@icloud.com>