metric.scores - input parameter col_IndexRegion should be col_IndexClass

[leppott]

Describe the bug
Function metric.scores input parameter col_IndexRegion should be col_IndexClass

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Expected behavior
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Additional context
When changed both BioMonTools and BCGcalc packages to use "Index_Class" and not "Index_Region" or other name (e.g., Site_Class) missed this one.

Will need to add a new input parameter to avoid breaking existing code that relies on the function (e.g., Shiny apps).

Place new variable, col_IndexClass, in the same slot and move col_IndexRegion to the end.

[leppott]

Ran PA Freestone IBI test and seems to work without error.

The example code has an error related to filter and single column data frames.