Smallest workspace address space

[tamirkamara]

Description

As a TRE Administrator
I want to allocate smaller address space to workspace
So that I better use the overall space available for the TRE.

Acceptance criteria

• A workspace can be created with a minimal CIDR, probably a /27 since app service minimum subnet is /28
• A workspace service that requires additional address space can make use of this new size. i.e. AML and databricks (need to verify if a /27 size is suitable first).