Changes

Add Xgc options for suballocator heap size and quick allocation

1. Use VMEM_ALLOC_QUICK by default for allocateRegion in
   allocate_memory32
2. Adds -Xgc:suballocatorQuickAllocDisable option that
   disables the default VMEM_ALLOC_QUICK
3. Adds -Xgc:suballocatorIncrementSize option that replaces the
   HEAP_SIZE_BYTES macro and controls the heap increment size
4. Adds an omrport_copy_suballocator_globals procedure that correctly
   initializes the PPG suballoctor globals for memCheckPortLib when
   -Xcheck is provided
5. Updates related documentation

Addresses: https://github.com/eclipse/omr/issues/7190
Signed-off-by: Nathan Henderson <nathan.henderson@ibm.com>
 (commit: f38831a)