Proto commits in nyaruka/phonenumbers

These 3 commits are when the Protocol Buffers files have changed:

Commit:dbc5179
Author:Rowan Seymour

Move metadata value types into a metadata package Regenerates phonemetadata.proto into a new metadata package (mirroring upstream's Phonemetadata) -- the only acyclic home for these types once the loader depends on them. The four value types (PhoneMetadata, NumberFormat, PhoneNumberDesc, PhoneMetadataCollection) are re-exported from the root package as type aliases, so the public API is unchanged; their hand-written helpers (Merge/HasPossibleLength/HasPossibleLengthLocalOnly) move with them and are now exported. The metadata loader/source code stays in root for now (a later step). Unblocks moving MatchNationalNumber into internal/ (#5b).

Commit:ab2a338
Author:Nic Pottier

save possible lengths to metadata, change implementation to use, add IS_POSSIBLE_LOCAL_ONLY and INVALID_LENGTH as possible return values to IsPossibleNumberWithReason

The documentation is generated from this commit.

Commit:0253355
Author:Nic Pottier

initial commit