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ARROW-7610: [Java] Finish support for 64 bit int allocations

Modified the `NettyAllocationManager` to allow for 64 bit allocations. If the requested size is > `Int.MAX_VALUE`, memory will be allocated using `PlatformDependent.allocateMemory(long)` otherwise the existing allocation method remains unchanged.

Unit tests were added that uses a custom AllocationManager with a smaller cutoff value to be able to test the new functionality within our current CI memory limits. Additional tests were added that allocate large buffers, but are required to run manually.

Closes #6323 from liyafan82/fly_0123_alloc

Authored-by: liyafan82 <fan_li_ya@foxmail.com>
Signed-off-by: Bryan Cutler <cutlerb@gmail.com>