fix: add missing ngc constants getter declarations and definitions

[Green-Sky]

This change is 

[Green-Sky]

should be a simple merge (if the ci plays nice...)
@JFreegman last chance to rename TOX_GROUP_MAX_PASSWORD_SIZE to TOX_GROUP_MAX_PASSWORD_LENGTH

[JFreegman]

should be a simple merge (if the ci plays nice...) @JFreegman last chance to rename TOX_GROUP_MAX_PASSWORD_SIZE to TOX_GROUP_MAX_PASSWORD_LENGTH

We should make a list of API breaking changes and save them all for the same commit.

[JFreegman]

Reviewed 4 of 4 files at r1, all commit messages.
Reviewable status: complete! 1 of 1 approvals obtained

[Green-Sky]

We should make a list of API breaking changes and save them all for the same commit.

for 0.3.0 ? :)

technically, the ngc api has still not been part of a release yet, so ... we could still change it now.

[JFreegman]

We should make a list of API breaking changes and save them all for the same commit.

for 0.3.0 ? :)

technically, the ngc api has still not been part of a release yet, so ... we could still change it now.

But it has been part of client releases, which means clients need to make a new release if we break the API

[codecov]

Codecov Report

Merging #2383 (2b1a6b0) into master (2e02d56) will increase coverage by 0.03%.
The diff coverage is 66.66%.

@@            Coverage Diff            @@
##           master   #2383      +/-   ##
=========================================
+ Coverage    9.95%   9.98%   +0.03%     
=========================================
  Files         141     141              
  Lines       32503   32530      +27     
=========================================
+ Hits         3235    3249      +14     
- Misses      29268   29281      +13     

Files Changed	Coverage Δ
toxcore/tox_test.cc	23.17% <0.00%> (-1.47%)	⬇️
toxcore/tox_api.c	71.28% <100.00%> (+6.22%)	⬆️

... and 5 files with indirect coverage changes