ss-1668 New app keywords form field to be used with Invenio records

[j-awada]

Description

Jira: https://scilifelab.atlassian.net/browse/SS-1668

This PR introduces changes for the autocomplete functionality of app tags using controlled text. The tags will be used as metadata in the Invenio records when minting an app.

To improve speed, pickled data; optimised for the autocomplete functionality and containing 1000s of entries, was used. The data is assembled separately using a standalone script. This data is loaded to memory on startup instead of being loaded during app creation. An API endpoint is used to query the data when a user starts typing a keyword.

Other changes include removing the current form field for free-text tags and using text from this new field introduced here as value for the attribute in the database. This will then be used during app filtering.

Data sources:

MeSH Medical Subject Headings
EuroSciVoc The European Science Vocabulary
GEMET General Multilingual Environmental Thesaurus

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