Closes #26425
## Overview
This PR adds support for specifying multiple environment files as
arguments when using the Deno CLI. Subsequent files override
pre-existing variables defined in previous files.
If the same variable is defined in the environment and in the file, the
value from the environment takes precedence.
## Example Usage
```bash
deno run --allow-env --env-file --env-file=".env.one" --env-file=".env.two" script.ts
```
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Co-authored-by: Bartek Iwańczuk <biwanczuk@gmail.com>
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.
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Co-authored-by: Bartek Iwańczuk <biwanczuk@gmail.com>
