Since our diagnostics use the `__FILE__` macro, they provide absolute
paths, which is kind of redundant and inconsistent: replace them with
relative ones.

As for debugging information, replacing absolute paths with relative ones
also requires an extra command to tell the debugger where to find the
source files, which is not convenient for developers: provide a new
`DEV_BUILD` option (turned off by default), which replaces absolute paths
with relative ones in debugging information if turned off.

Strip the prefix map flags from compiler flags exported to tarantool via
`src/trvia/config.h`.

Closes #7808

NO_DOC=<verbosity>
NO_TEST=<verbosity>