Add virusMetadata to DataSpaceConnection object

[helenmiller16]

Description

Allow access to virus metadata for viruses used in NAb assays in DataSpace.

Example

> con <- connectDS()
> head(con$virusMetadata)
   assay_identifier        virus     virus_type neutralization_tier clade antigen_control
1:          NAB MAB 0013095-2.11 Env Pseudotype                   2  <NA>               0
2:          NAB MAB  001428-2.42 Env Pseudotype                   2     C               0
3:          NAB MAB  0041.v3.c18 Env Pseudotype                   2     C               0
4:          NAB MAB  0077.v1.c16 Env Pseudotype                   2     C               0
5:              NAB    00836-2.5 Env Pseudotype                  1B     C               0
6:          NAB MAB   0260.v5.c1 Env Pseudotype                   2     A               0
                  virus_full_name virus_name_other virus_species virus_host_cell virus_backbone
1: 0013095-2.11 [SG3Δenv] 293T/17             <NA>           HIV         293T/17        SG3Δenv
2:  001428-2.42 [SG3Δenv] 293T/17             <NA>           HIV         293T/17        SG3Δenv
3:  0041.v3.c18 [SG3Δenv] 293T/17      0041.V3.C18           HIV         293T/17        SG3Δenv
4:  0077.v1.c16 [SG3Δenv] 293T/17      0077.v1.c16           HIV         293T/17        SG3Δenv
5:    00836-2.5 [SG3Δenv] 293T/17             <NA>           HIV         293T/17        SG3Δenv
6:   0260.v5.c1 [SG3Δenv] 293T/17       0260.V5.C1           HIV         293T/17        SG3Δenv
            panel_names
1: Tiered diverse panel
2: Tiered diverse panel
3:                 <NA>
4:                 <NA>
5: Tiered diverse panel
6: Tiered diverse panel