ADS Not Parsing :error in SQLCMD t-sql script

[DigitalDuquette]

• Azure Data Studio Version: 1.38
• OS Version: macOS, Windows 10

Steps to Reproduce:

1. Use the following script the :error sqlcmd causes failure of script with error

   
   USE [edw]; 
   GO 
   :setvar ExecPath "/Users/jaredduquette/GitHub/PADNOS-data-warehouse/miscellany/sqlcmd/"
   :setvar Error "errors.txt"

:error "/Users/jaredduquette/GitHub/PADNOS-data-warehouse/miscellany/sqlcmd/tsql-script/errors.txt" !!:GO

3. Same script files used to test as in issue #20119 
4. ADS in Windows and macOS both stable and insiders gives error: 
<img width="412" alt="Screen Shot 2022-08-12 at 11 31 15 AM" src="https://user-images.githubusercontent.com/47231954/184388832-f7bca8f6-0049-4b89-bc4d-b78ffd5f32a7.png">

**Windows SSMS (working)**
![Screen Shot 2022-08-12 at 11 24 49 AM](https://user-images.githubusercontent.com/47231954/184388957-1fa9a6a6-0c38-43ea-a759-fd5ab70a46e5.png)

**Windows ADS (not working)**
![Screen Shot 2022-08-12 at 11 25 57 AM](https://user-images.githubusercontent.com/47231954/184388980-70df1f49-b498-4ec3-80f7-2068e38752b1.png)

**macOS ADS (not working)**
<img width="1060" alt="Screen Shot 2022-08-12 at 11 24 35 AM" src="https://user-images.githubusercontent.com/47231954/184389006-6817555c-bbf2-4493-acb0-83422b1ae272.png">

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[alanrenmsft]

I looked into the code and looks like the error command is explicitly marked as not supported in ADS. I have to dig more into the commit history/pr descriptions to find out why.

[alanrenmsft]

Didn't find anything useful in the commit history, it is not mentioned why the :error is not implemented. I'll put it in backlog and let our PM @erinstellato-ms to decide the priority of this task.