R4 Xt-EHR mapping

[oijauregui]

• Add R4 columns and data to xtehr-model-mapping.tsv
• Add logic to js script to render R5 and R4 columns in mapping pages

Review builds:

• R5 https://build.fhir.org/ig/oijauregui/ehdsimaging-r5/branches/R4-mapping-multiversion/en/
• R4 https://build.fhir.org/ig/oijauregui/ehdsimaging-r4/branches/R4-mapping-multiversion/en/

[oijauregui]

@bvdh I would like to have both R4 and R5 mapping on the same table for both builds. But the table is too wide to fit in the page, what do you think?