[AppService] Bugfix: Better error handling when trying to create duplicate ASP in diff location

[calvinsID]

Description
Fixes #16008

When using az webapp up to create an app with existing ASP in a different location, we show the following unhandled error message (notice UnknownError):

This PR is to handle the error msg:

Testing Guide

• run az webapp up --location location1 --name name1
• re-run using different name and location. plan should be defaulted to the same plan created from the first invocation of the command. az webapp up --location location2 --name name2

Should get error message saying ASP exists in different location
cls

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[panchagnula]

so this repros with or without --html flag - I think the reported error was specific to --html parameter used in the command

[panchagnula]

LGTM

[yonzhan]

AppService

[qwordy]

CLIError is not recommended any more. @houk-ms
https://github.com/Azure/azure-cli/blob/dev/doc/error_handling_guidelines.md

[qwordy]

Is CLIError allowed? @houk-ms @yungezz

[qwordy]

@calvinsID Thank you for updating error type!