Fix generics with package alias

[sdghchj]

Describe the PR
fix generics bug:

1. More than one generics types, including parameter types, actually come from different packages, but with the same short package name and type name.
2. Import generics types from a package with an alias.

View details in ./testdata/generics-package-alias

Now we determine mode type name conflict during the phase of collecting types, no longer determine during the parsing phase.

Relation issue
#1353

[codecov]

Codecov Report

Base: 95.68% // Head: 95.70% // Increases project coverage by +0.02% 🎉

Coverage data is based on head (be7f3d8) compared to base (277a278).
Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1360      +/-   ##
==========================================
+ Coverage   95.68%   95.70%   +0.02%     
==========================================
  Files          14       14              
  Lines        2894     2818      -76     
==========================================
- Hits         2769     2697      -72     
+ Misses         70       67       -3     
+ Partials       55       54       -1     

Impacted Files	Coverage Δ
generics_other.go	100.00% <ø> (ø)
schema.go	100.00% <ø> (ø)
generics.go	100.00% <100.00%> (ø)
packages.go	92.17% <100.00%> (+1.22%)	⬆️
parser.go	93.68% <100.00%> (-0.20%)	⬇️
types.go	100.00% <100.00%> (ø)

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

☔ View full report at Codecov.
📢 Do you have feedback about the report comment? Let us know in this issue.

[ubogdan]

LGTM