Fix IdentifierName issue in snippet templates with placeholder for symbolic name

[bhsubra]

Changes to return placeholder text as IdentifierName instead of <error> for snippet templates with placeholder text for symbolic name

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

[majastrz]

Returning <error> for a malformed identifier is the expected behavior in a Bicep file. I'm very hesitant to relax any validation in the compiler pipeline just for snippets.

Can you tell me more why returning <error> for the IdentifierName is a problem for snippets?

[majastrz]

skipped

This relies on a specific parser recovery behavior, which makes it kind of fragile. (We also want to avoid regexes in the main compiler path.)

If we agree that we need to support it in the parser (see my other comment), it should be its own type of syntax node and parsed by the parser like everything else.

[bhsubra]

Thanks Marcin, I'll investigate separate syntax node option and see how it goes.

[bhsubra]

Returning <error> for a malformed identifier is the expected behavior in a Bicep file. I'm very hesitant to relax any validation in the compiler pipeline just for snippets.

Can you tell me more why returning <error> for the IdentifierName is a problem for snippets?

Having a malformed identifier makes it difficult to figure out resource dependencies in snippet templates with multiple resources. I am wondering if we should skip having placeholder for symbolic name of parent resource in templates with multiple resources.
E.g:

// Automation Module
resource ${1:automationAccountVariable} 'Microsoft.Automation/automationAccounts/modules@2015-10-31' = {
  parent: automationAccount
  name: ${2:'name'}
  properties: {
    contentLink: {
      uri: ${3:'https://content-url.nupkg'}
    }
  }
}

resource automationAccount 'Microsoft.Automation/automationAccounts@2015-10-31' = {
  name: ${4:'name'}
}

@MarcusFelling , for snippet templates with multiple resources, do you think it's okay to skip having placeholder for parent resource symbolic name for now?

[bhsubra]

Had an offline discussion with @MarcusFelling. We'll skip adding placeholder for parent resource symbolic name. Made changes to flip ordering of resources to display parent resource first in this PR:#2172

I'll go ahead and close this PR. @majastrz , let me know if you have any concerns.