Conda custom packages support

[Kr0n0]

Small changes for adding support for Conda custom packages in addition to the pip ones.

• Deleted custom-packages-example.txt and replaced by two files : custom-packages-example.conda (for Conda packages) and custom-packages-example.pip (for Pip ones).
• Renamed custom-packages to custom-packages.pip.
• Modified run-extended.sh to be able to insert into the generated Dockerfile the conda install command only if the custom-packages.conda exists.

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[Kr0n0]

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