Add optional format flag for listaccounthistory

[dcorral]

What kind of PR is this?:

/kind feature

What this PR does / why we need it:

Adds optional parameter format to listaccounthistory with following possible values:

• 'id' -> "amounts@id" (i.e "10@0")
• 'symbol' (default) -> "amounts@symbol" (i.e "10@DFI")