By passing a string_view, the function can take std::string and
C-style strings (or obviously string_views).

Most callers had an std::string, with known length, then passed
the C-style string, which has no length information, and the function
then would redetermine the length.

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>

Turns out some libdivecomputer devices add spurious whitespace
to the firmware.

Remove any spurious leading/trailing whitespace when importing
the dive computer extra_data to struct divecomputer.

For now, the sanitized string is not written back to the logs.
When (if) libdivecomputer removes that whitespace it might be a
good idea to write the sanitized string back to the log, for
consistency.

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>