Add `.get_main_tags()` or `.get_main_dicom_tags()` alias for `.get_main_information()` methods

[gacou54]

For each resource, the main tags are retrieved with the .get_main_information() method. However, the Orthanc nomenclature refers to the main DICOM tags as the "main dicom tags".

I suggest adding an alias to the get_main_information() method named get_main_tags() or get_main_dicom_tags() to be consistent with Orthanc nomenclature.

[gacou54]

Actually the get_main_information() method retrieves the information of the resource (if stable, last update, labels, main dicom tags, etc.).

I think adding a <Resource>.main_dicom_tags property might be best to retrieve only the main DICOM tags.

[gacou54]

<Resource>.main_dicom_tags method added in PyOrthanc 1.16.1