[B] DIS-364 resolve errant FAIR scores

[leojpod]

• installs a new package to perform string validations
• use it to only send FAIR score requests if the externalId is a valid URL (i.e. a DOI)

To test it on dev:

• go to -> https://discover-dev.repositive.io/datasets/07ca4a9e-de64-4233-8f42-bba48e6473cc
• the FAIR score should be grey