OTA-2320: Add an option to aktualizr-info to print delegations metadata

[mike-sul]

Signed-off-by: Mike Sul ext-mykhaylo.sul@here.com

1. Added an option --delegate to aktualizr-info aimed to print delegations metadata;
2. Added corresponding tests.

[lbonn]

Any reason not to use std::pair? And shouldn't role_name be the first field?

Probably a matter of test but also not sure if it's worth it adding this type synonym in the header: in client code, we'd have one std::vector<std::pair<Uptane::Role, std::string>>, and the rest can be deduced via auto.

[mike-sul]

And shouldn't role_name be the first field?
Why should it be the first ? I think, it makes sense to preserve the same field order as in the DB table.

Any reason not to use std::pair?
The reason, I decided to go with std::tuple over std::pair is the fact that the later can accommodate just two fields while the former can have arbitrary number of them what can be handy in case if the table schema changes (more than two fields or just one field).

Probably a matter of test but also not sure if it's worth it adding this type synonym in the header: > in client code, we'd have one std::vector<std::pair<Uptane::Role, std::string>>, and the rest can > be deduced via auto

I think, it makes sense to use Uptane::Role regardless of the type been declared or not, it will make the type more clear and explicit.

Regarding introduction of the new type. IMHO, there are several pros over not doing it:

1. if the type is changed then you don't need to change it in every spot where it's used;
2. if adding some methods is required then the type declaration can be replaced with corresponding struct/class;
3. less typing (at the moment it's used in the storage interface, DB storage interface, DB storage implementation and at least once for each client (although auto cannot be used in function declarations/signature)

In general, it improves Extensibility and Maintainability.

Having said that, I don't mind to get rid of the type declaration since this is very unlikely that loadAllDelegations() will have more than two clients, i.e. aktualizr-info and its tests.

[mike-sul]

Pushed code with the changes implied here.

[codecov-io]

Codecov Report

Merging #1138 into master will decrease coverage by <.01%.
The diff coverage is 80.64%.

@@            Coverage Diff             @@
##           master    #1138      +/-   ##
==========================================
- Coverage   76.17%   76.17%   -0.01%     
==========================================
  Files         164      164              
  Lines        9869     9904      +35     
==========================================
+ Hits         7518     7544      +26     
- Misses       2351     2360       +9

Impacted Files	Coverage Δ
src/libaktualizr/storage/sqlstorage.h	50% <ø> (ø)	⬆️
src/libaktualizr/storage/invstorage.h	97.43% <ø> (ø)	⬆️
src/libaktualizr/storage/sqlstorage.cc	74.02% <76.47%> (+0.58%)	⬆️
src/aktualizr_info/main.cc	90.4% <85.71%> (+0.3%)	⬆️
src/libaktualizr/package_manager/ostreemanager.cc	64.37% <0%> (-3.44%)	⬇️
src/libaktualizr/storage/sql_utils.h	83.09% <0%> (+1%)	⬆️

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[pattivacek]

LGTM. @mike-sul do you want to merge now despite the TODO in SpawnProcess? This is higher-priority anyway and if you come back to fix that up later than I don't see a problem.

[mike-sul]

LGTM. @mike-sul do you want to merge now despite the TODO in SpawnProcess? This is higher-priority anyway and if you come back to fix that up later than I don't see a problem.

Yes, anyway the TODO depends on the other PR that hasn't been merged yet.