Handle C-ECHO request in storeSCP CLI tool

[PierreBou91]

This commit adds support for handling C-ECHO requests in the storeSCP CLI tool. With this update, the storeSCP tool can now process incoming C-ECHO requests and send appropriate responses.

Related to issue #337

Before screenshot:

After screenshots:

It appears that the main functionality of the storescp is maintained:

All test passed after cargo test

The changes in transfer.rs were relevant to:

1. Remove duplicates SOPClasses.
2. Add the Verification SOP Class necessary for the presentation context.

Please tell me if any additions / modification / deletion are needed.

[Enet4]

Thank you for looking into this feature, @PierreBou91!

Could you please rustfmt this source file? The changes added do not seem to follow the rest of the formatting.

Minor suggestion inline.

[PierreBou91]

I forgot to fmt, apologies for that.

Thanks for the suggestion regarding the switch to InMemDicomObject::from_element_iter, I also made the modification for create_cstore_response as I felt like it was the same scenario.

[PierreBou91]

I also got rid of the useless array in create_cstore_response so it matches your modifications. The built version seemed to work fine.
Thanks for your time and advices @Enet4 !

[Enet4]

Just tried it out in practice and it appears to be responding well to C-ECHO requests. Found no regressions of the standard storage service either, so this is good to enter! Thank you very much!