Implement Arrow C struct <=> sparrow classes conversion functions

[JohanMabille]

These functions should allow the following:

• Build a sparrow array from Arrow C data structures, taking ownership of the memory; the C data structures can be safely destroyed
• Build a sparrow array from Arrow C data structures, not taking ownership of the memory; the C data structures must be kept alive
• Build Arrow C data structures from sparrow array, taking ownership; the C releaser should be set accordingly befor the sparrow array is destroyed
• Build Arrow C data structures from sparrow array, not taking ownerhips; the C releaser should be the null pointer, and the sparrow array should be kept alive.

[JohanMabille]

The conversion functions transfering the ownership have been implemented in #79. The missing functions need #106 to be implemented first.