Add XTDB support to Labs

[planetf1]

XTDB is our most capable repository for Egeria.

I propose to add support for XTDB for our Lab notebooks. Note: this requires other changes - local configuration, docs etc

I propose to add 2 configurations:

• inmemory

• persistent

  The latter will be a simple, single option

  In our charts repo, a similar change will be made for the base chart (see https://github.com/odpi/egeria-charts/issues/125) Over there we'll also document the configuration to have the xtdb connector loaded (possibly via https://github.com/odpi/egeria/issues/7224 )

HA/multi replica is excluded as is generic configuration (for now)

[planetf1]

The initial change has been made @dwolfson not sure if you wish to add more? Assigning