CORE-2026: allocate shared memory if the tool is configured to use it

[slr71]

This change allows DE administrators to indicate that an app should have shared memory allocated to it for tools that require shared memory. We provide the shared memory by creating an emptyDir volume with the size limit specified by the tool. (See this StackOverflow answer for more details.)

This is implemented in a similar way to our GPU integration. To dedicate shared memory to a tool add a container device to the tool with a host path of /dev/shm and a container path equal to the amount of shared memory to make available:

It's not a perfect way to indicate how much shared memory should be provided, but implementing it this way allowed us to make this feature available quickly.

[johnworth]

The only change I can think of is to move "/dev/shm" references into a constant, but that's minor.