Fix: Include explicit sources in export command

[shiumachi]

This PR addresses an issue where the poetry export command was not exporting the --extra-index-url and --trusted-host options as expected for explicit sources.

Previously, the Exporter class was calling the repositories property from the RepositoryPool in the poetry package to fetch all repository information. However, repositories excludes explicit repositories.

To resolve this issue, I have modified the Exporter class to use the all_repositories property instead of repositories. The all_repositories property includes explicit repositories and ensures the --extra-index-url and --trusted-host options are exported correctly.

fixes: #204

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
1 Code Smell

No Coverage information
0.0% Duplication

[shiumachi]

I understand the concern raised by SonarCloud regarding the usage of HTTP. However, in the context of this PR, this alert can be safely ignored.

The code snippet in question aligns with existing code found here:
https://github.com/python-poetry/poetry-plugin-export/blob/main/tests/test_exporter.py#L1583

[radoering]

You can ignore SonarCloud. Maintainers just have to review if it's relevant or not (as in this case).