Make the crashdump runtime configurable

[jsturtevant]

Some feedback from users was they would like to see the crashdump be runtime configurable

[dblnz]

The crashdump feature has been merged with #417.
It support following options:

• The crashdump feature toggles the logic of the creation of core dumps for Hyperlight Sandboxes.
• Additionally, core dumps can be configured at the Sandbox level.
  By default, all the Sandboxes have core dump generation enabled. The user can set the guest_core_dump = false in the SandboxConfiguration to disable core dumps for specific Sandboxes.
• By default, Hyperlight places the core dumps in the temporary directory (platform specific).
  To change this, HYPERLIGHT_CORE_DUMP_DIR env variable can be used to specify a directory.
  If the directory does not exist, the temporary directory is used.