This commit makes `bcc_resolve_symname` to take an `bcc_symbol_option`
parameter, and pass it to underlying calls to control symboling behavior.
When `NULL` is passed, it will fallback to default which is current
behavior that uses debug file, verify debug file CRC, and check all
types of symbols.

This commit also removes the unneccesary intermediate
`bcc_find_symbol_addr`.

Added documentation for usage of the API, updated most call sites to use
default with `NULL`, and fixed some memory leaks at call sites.