[Suggestion] It would be better if add a validation when entering a function app name contains "--"

[v-mengwe]

OS: Win10
Azure Resource Extension Build Version: 20220518.13
Azure Function Extension build Version: 20220517.4

Repro Steps:

1. Right click "Function App" Node -> Create Function App in Azure -> Enter a function app name contains "--", e.g. "elsa--test".
2. Check whether there is a validation when entering a function app name contains "--".

Actual:

1. There is no validation when entering a function app name contains "--".
   
2. Fail to create the function app with an error.
   

Suggestion:
It would be better if add a validation when entering a function app name contains "--".

[alexweininger]

We could try to use the check resource name API to validate resource names to prevent bugs like this.

https://docs.microsoft.com/en-us/rest/api/resources/check-resource-name/check-resource-name