[clang-format] Add a SpaceAroundPointerQualifiers style option

Some projects (e.g. FreeBSD) align pointers to the right but expect a
space between the '*' and any pointer qualifiers such as const. To handle
these cases this patch adds a new config option SpaceAroundPointerQualifiers
that can be used to configure whether spaces need to be added before/after
pointer qualifiers.

PointerAlignment = Right
SpaceAroundPointerQualifiers = Default/After:
void *const *x = NULL;
SpaceAroundPointerQualifiers = Before/Both
void * const *x = NULL;

PointerAlignment = Left
SpaceAroundPointerQualifiers = Default/Before:
void* const* x = NULL;
SpaceAroundPointerQualifiers = After/Both
void* const * x = NULL;

PointerAlignment = Middle
SpaceAroundPointerQualifiers = Default/Before/After/Both:
void * const * x = NULL;

Reviewed By: MyDeveloperDay

Differential Revision: https://reviews.llvm.org/D88227