Provide URI for metadata elements

[ferrighi]

We should add information on URI for some of our MMD elements. There are some easy to achieve:

• KEYWORD_URI (these are keywords that are not GCMD)
• PARAMETER_URI (GCMD Science keywords)
• ORGANIZATION_URI

[ferrighi]

For keyword and parameters we have all info into vocab (also mapping to authoritative sources).

For example:

using nerc/nasa:

<keywords vocabulary="CFSTDN">  
   <keyword uri="http://vocab.nerc.ac.uk/collection/P07/current/CFSN0023/">air_temperature</keyword>  
</keywords>

<keywords vocabulary="GCMDSK">  
   <keyword uri="https://gcmd.earthdata.nasa.gov/kms/concept/f634ab55-de40-4d0b-93bc-691bf5408ccb">EARTH SCIENCE > ATMOSPHERE > ATMOSPHERIC TEMPERATURE > SURFACE TEMPERATURE > AIR TEMPERATURE</keyword>  
</keywords>

OR using vocab.met

<keywords vocabulary="CFSTDN">
   <keyword uri="https://vocab.met.no/CFSTDN/air_temperature">air_temperature</keyword>
</keywords>
<keywords vocabulary="GCMDSK">
   <keyword uri="https://vocab.met.no/GCMDSK/f634ab55-de40-4d0b-93bc-691bf5408ccb">EARTH SCIENCE > ATMOSPHERE > ATMOSPHERIC TEMPERATURE > SURFACE TEMPERATURE > AIR TEMPERATURE</keyword>
</keywords>

OR using id and resource

<keywords vocabulary="CFSTDN">  
   <keyword id="CFSN0023">air_temperature</keyword>  
   <resource>http://vocab.nerc.ac.uk/collection/P07/current/</resource>  
</keywords>

<keywords vocabulary="GCMDSK">  
   <keyword id="f634ab55-de40-4d0b-93bc-691bf5408ccb">EARTH SCIENCE > ATMOSPHERE > ATMOSPHERIC TEMPERATURE > SURFACE TEMPERATURE > AIR TEMPERATURE</keyword>  
   <resource>https://gcmd.earthdata.nasa.gov/kms/concept/</resource>  
</keywords>

For organisation we can do something similar and develop https://vocab.met.no/mmd/en/page/Organisation adding aliases and ROR ids