arrow

GH-34630: [C++] Second block of refactoring to move acero out of libarrow (#34575)

### Rationale for this change

This is the second and last block of refactoring before moving acero out
of libarrow. This PR removes the remaining dependencies from libarrow
into the compute/exec directory.

### What changes are included in this PR?

In detail:

* compute/exec/expression is moved inside compute since it is needed in
several kernels
* all compute/exec specific include files are removed from compute/api.h
* light_array_exec_test.cc i(introduced in the previous refactoring) s
merged back into light_array_test
* testing generators are refactored to remove the need for
exec/options.h
* some utilities are moved from compute/exec/util to compute/util
* updated python and r libraries usage of moved files

### Are these changes tested?

Yes using existing tests (some of which have been updated due to
refactoring).

### Are there any user-facing changes?

no
* Issue: #15280
* Closes: #34630