Proto commits in mennanov/fmutils

These 4 commits are when the Protocol Buffers files have changed:

Commit:22122cd
Author:Daniel Mack
Committer:Daniel Mack

testproto: add nested map fields

The documentation is generated from this commit.

Commit:af9ce0f
Author:Renat Mennanov

Upgrade google.golang.org/protobuf to v1.26.0

Commit:bf40c03
Author:Renat Mennanov

Add support for repeated message fields.

Commit:d93816c
Author:Renat Mennanov
Committer:Renat Mennanov

Initial code