fix: --env flag missing file/wrong syntax of file raises error

[Hasan-Alrimawi]

Enhanced warning message for --env flag with run and eval subcommands.

The commit is specifically made to address issue #23674 by improving the warning messages that appear when using the --env flag with run or eval subcommands in the following scenarios:

1. Missing environment file.
2. Incorrect syntax in the environment file content.

Changes made

• Distinguishes between cases of missing environment file and wrong syntax in the environment file content.
• Shows a concise warning message to convey the case/issue occurred.

Code changes & enhancements

• Implemented a match statement to handle different types of errors received while getting and parsing the file content to display a concise warning message, rather than simple error check and then displaying the same warning message for whatever the type of error is.
• Updated the related existing tests to reflect the new warning messages.
• Added two test cases to cover the wrong environment file content syntax with both run and eval subcommands.

Impact
The use of --env flag with both run/eval would be more user-friendly as it gives a precise description of what is not right when using incorrectly.

If you could give it a look, @dsherret , I appreciate your feedback on these changes.

[CLAassistant]

All committers have signed the CLA.

[Hasan-Alrimawi]

@bartlomieju
Could you please take a look in order to merge the changes if everything is good? All checks have passed.