Bicep compat functions

[SteveL-MSFT]

Summary of the new feature / enhancement

Need equals() and format() functions implemented

Proposed technical implementation details (optional)

No response

[andyleejordan]

Also needs if() as discovered while testing #770 against:

@allowed(['light', 'dark'])
@description('Light or dark color mode')
// TODO: Teach DSC how to use Bicep param files
param colorMode string = 'light'

var valueData = colorMode == 'light' ? 1 : 0

The ARM file ends up with [if(equals(parameters('colorMode'), 'light'), 1, 0)].

Per https://learn.microsoft.com/en-us/azure/azure-resource-manager/templates/template-functions-logical#if

that's if(condition, trueValue, falseValue) and comes from Bicep's ternary operator.