Show a more meaningful error when sending code to the Python terminal.

[guoci]

If there is any syntax error in the file where the user sends code, deprecated will be sent to the Python terminal. This PR modifies to show the exception from ast.parse.
Related: #25117

[guoci]

@microsoft-github-policy-service agree

[anthonykim1]

Thanks for the PR, I'm not sure how useful the error would be though.

Usually it means we weren't able to do the "smarts" for smart send in terms of ast parsing the python file properly bc of outdated python version or invalid syntax somewhere in the file.

What were the outputs you would see with this PR?

[guoci]

import this

if True
    pass

import this

For the above code, when there is invalid syntax, originally, the output will be:
deprecated
But with this PR, the output changes to:
'vscode-python error: SyntaxError("expected \':\'", (\'<unknown>\', 2, 8, \'if True\\n\', 2, 9))'
which gives the location of the syntax error.