Add xml paths for active Topo metrics belonging to a schema

[volkcj]

QA - Topo Channel Metrics
Tier 1
Tier 2
ChUnitAreaPoly (dupe of Poly Area?)

QA - Topo Tier 1 Metrics
-DpthResid
-DpthThwgExit
-DpthThwgMax_Avg

QA - Topo Tier 2 Metrics
-DpthResid
-DpthThwgExit
-DpthThlwgMax_Avg

QA - Topo Visit Metrics
-Bf_Island_Ct
-BedGrad (low priority)
-Wet_Island_Ct
-WetMChnl_Area (low priority)