Feature request: user inputs for the forest plot in the "Meta" tab

[jmb01]

Some helpful feature would include user inputs like:

• Select target
• Optionally select a faceting variable from: outcome, TAR. The vertical faceting should always be by database, but if the user wants to also facet by outcome or TAR, they can be laid out in separate columns.
• Select values for remaining variables besides target, comparator, faceting variable
• Optionally select from among the available comparators, but deal with them in same way you currently do (i.e., separate lines for each in the plot, with Comp1, Comp2 noted in the caption)
• Toggle x-axis between free or user specified range (and truncate error bars as needed with a marker, usually an arrow, to indicate truncation)
• Toggle to either include only unblinded databases (the current behavior) or to add empty panels for databases that have no data or are blinded.