Fwd picodst integration

[jdbrice]

Adds initial PicoDst integration for Forward systems:

• StPicoFwdTRack
• StPicoFcsHit
• StPicoFcsCluster

Note: some stashed files got into this commit, will remove. Only StRoot/StPico* is intended for this PR

[nigmatkulov]

Not sure if this type of initialization is allowed in ROOT5. I would move it to the constructor.

[genevb]

From the discussion at this week's analysis meeting, it sounds like we should freeze an SL24a library shortly after this code is merged, perhaps after a day of testing it in DEV, as there is interest in using it in the ongoing preview production of Run 22 data (which is already resuming without this).