[SYSTEMDS-3867] Safe Fast Frame Copy

[yj-40-56]

Student project for DIA at TU Berlin: improving copy()

[yj-40-56]

Replaced Locking on ValueType.BOOLEAN with locking based on ArrayType:

• BitSetArray requires locking due to underlying storage in longs. Small Array are safe if they are shorter than 64 rows (using underlying Byte[]) a. Once above that threshold, the array is turned into a BitSetArray

• OptionalArray has an underlying null-mask, indicating the null entries. That null-mask is based on a BitSetArray and is not thread-safe.

Additional ArrayTypes that are locked:

• RaggedArray: internal resizing should cause race conditions. The set()/append() methods all contained a reset() into set() segment which has no guarantee of being atomic.
• DDCArray/ACompressedArray: Similar to RaggedArrays, modifications are not atomic.

I have verified the fix for BitSetSArray and OptionalArray.

I did not include tests for RaggedArray and ACompressedArray. After looking at the implementations, I am convinced they are not thread-safe, but I was not able to create unit tests to show that specific behaviour.