Add JSON converters for container and acl structures

[alexvanin]

With neofs-api v2.0.1 release we have more JSON name attributes and rich documentation. To use JSON representation of container and extended ACL in neofs-cli we have to update neofs-api-go library.

[codecov]

Codecov Report

Merging #173 into master will increase coverage by 2.40%.
The diff coverage is 40.84%.

@@            Coverage Diff             @@
##           master     #173      +/-   ##
==========================================
+ Coverage   38.38%   40.78%   +2.40%     
==========================================
  Files          71       74       +3     
  Lines        8219     8284      +65     
==========================================
+ Hits         3155     3379     +224     
+ Misses       4625     4435     -190     
- Partials      439      470      +31     

Impacted Files	Coverage Δ
v2/acl/types.go	80.00% <ø> (+40.00%)	⬆️
v2/object/marshal.go	59.06% <0.00%> (ø)
v2/refs/marshal.go	56.45% <0.00%> (ø)
v2/acl/json.go	38.46% <38.46%> (ø)
v2/container/json.go	38.46% <38.46%> (ø)
v2/netmap/json.go	38.46% <38.46%> (ø)
pkg/acl/eacl/target.go	100.00% <100.00%> (ø)
v2/acl/convert.go	70.54% <100.00%> (+35.27%)	⬆️
... and 7 more

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[realloc]

LGTM