This commit converts the license handling to adhere to the REUSE
specification. It specifically:
1. Adds used licnses to LICENSES/ directory
2. Add "isc" template for adding the copyright boilerplate
3. Changes all source files to include copyright and SPDX license
header, this includes all the C sources, documentation, zone files,
configuration files. There are notes in the doc/dev/copyrights file
on how to add correct headers to the new files.
4. Handle the rest that can't be modified via .reuse/dep5 file. The
binary (or otherwise unmodifiable) files could have license places
next to them in <foo>.license file, but this would lead to cluttered
repository and most of the files handled in the .reuse/dep5 file are
system test files.
Add a new function to resize the number of counters in a statistics
counter structure. This will be needed when we keep track of DNSSEC
sign statistics and new keys are introduced due to a rollover.
Add a simple stats unit test that tests the existing library functions
isc_stats_ncounters, isc_stats_increment, isc_stats_decrement,
isc_stats_set, and isc_stats_update_if_greater.
