Return valid IdentifierName for declarations with placeholder text for symbolic name

[bhsubra]

Snippet templates available here: https://github.com/Azure/bicep/tree/main/src/Bicep.LangServer/Snippets/Templates have placeholder text for symbolic name. We seem to return <error> as IdentiferName while parsing. We should be returning placeholder text instead. Consider below example:
resource ${1:dnsZone} 'Microsoft.Network/dnsZones@2018-05-01' = {
name: ${2:'name'}
location: 'global'
}

We should return ${1:dnsZone} as IdentifierName in this case

[alex-frankel]

Closing - we decided not to fix this