Linking artifacts and publications

Fixes

Partially addresses #122 (closed)

Description

• Set of features for linking artifacts to publications.
• Removal of unnecessary files (mainly public files for the table artifacts_publications since this is an admin-only feature).

Type of PR

This PR is a feature.

Technicalities

There are 3 ways for linking artifacts to publications:

1. Through the selected publication. (Artifacts can be linked to a particular publication through edit feature of that publication)
2. Through the selected artifact. (Publications can be linked to a particular artifact through edit feature of that artifact)
3. Through the view page for all links. (Any publication can be linked to any artifact through the edit feature)

Tests

For Artifacts-Publications link, steps for testing each of the above 3 ways:

1. /admin/artifacts-publications/add/1/<publication_id>
2. /admin/artifacts-publications/add/2/<artifact_id>
3. /admin/artifacts_publications

Note - The features are made based on the modified database structure cdli_db_final_schema. For testing, load the artifacts_publications table from the new database.

The features are ready for testing.