Better align organization roles with currently existing roles

[wetret]

Currently, the organization roles do not perfectly align with the ones defined in MII official documents and are therefore substituted in MII processes by roles that do not fit perfectly.

Possible changes include adding "DMS" as a central organisational role in the MII and renaming "MeDIC" to "DIC" to align the wording with the official documents of the MII and so that all roles consist of three letters.

This leads to the following proposal for roles in DSF v1.0.0:

<concept>
  <code value="COS"/>
  <display value="Coordinating Site"/>
</concept>
<concept>
  <code value="CRR"/>
  <display value="Central Research Repository"/>
</concept>
<concept>
  <code value="DIC"/>
  <display value="Data Integration Center"/>
</concept>
<concept>
  <code value="DMS"/>
  <display value="Data Management Site"/>
</concept>
<concept>
  <code value="DTS"/>
  <display value="Data Transfer Site"/>
</concept>
<concept>
  <code value="HRP"/>
  <display value="Health Research Platform"/>
</concept>
<concept>
  <code value="TTP"/>
  <display value="Trusted Third Party"/>
</concept>

@MadMax93 @hhund any thoughts or additions?