Add a find-string-mapping function.

[tmccombs]

Provide a way for user code to access mappings
in string-vector-mappings without having to use an non-exported symbol.

[luismbo]

The mappings in the babel-package should be an implementation detail and they're quite inconvenient to deal with. What's your use case?

[tmccombs]

I want to decode/encode from a vector into an existing vector, rather than creating a new octet vector or string.