add cli flag --pdl to determine whether parse operations in dependency

[sdghchj]

Describe the PR
Add cli flag --pdl to determine whether parse operations in dependency

swag init --pd            // for backward compatibility, only parse models indepedency
swag init --pdl 3        // 0 disabled, 1 only parse models, 2 only parse operations, 3 parse all

Relation issue
#1451

[codecov]

Codecov Report

Patch coverage: 78.57% and no project coverage change.

Comparison is base (e73a0d0) 83.76% compared to head (3e3eaff) 83.76%.

❗ Current head 3e3eaff differs from pull request most recent head b43eb93. Consider uploading reports for the commit b43eb93 to get more accurate results

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1605   +/-   ##
=======================================
  Coverage   83.76%   83.76%           
=======================================
  Files          19       19           
  Lines        3752     3752           
=======================================
  Hits         3143     3143           
  Misses        521      521           
  Partials       88       88           

Impacted Files	Coverage Δ
gen/gen.go	92.60% <ø> (ø)
packages.go	89.12% <50.00%> (ø)
parser.go	93.82% <77.77%> (ø)
golist.go	90.24% <100.00%> (ø)

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