vector: Traversal, retrieval, insert and locking enhancements

Renamed AST_VECTOR_INSERT to AST_VECTOR_REPLACE because it really
does replace not insert.  The few users of AST_VECTOR_INSERT were
refactored.  Because these are macros, there should be no ABI
compatibility issues.

Added AST_VECTOR_INSERT_AT that actually inserts an element into the
vector at a specific index pushing existing elements to the right.

Added AST_VECTOR_GET_CMP that can retrieve from the vector based
on a user-provided compare function.

Added AST_VECTOR_CALLBACK function that will execute a function
for each element in the vector.  Similar to ao2_callback and
ao2_callback_data functions although the vector callback can take
a variable number of arguments.  This should allow easy migration
to a vector where a container might be too heavy.

Added read/write locked vector and lock manipulation macros.

Added unit tests.

ASTERISK-25045 #close

Change-Id: I2e07ecc709d2f5f91bcab8904e5e9340609b00e0