Unexport types and functions cataloger packages (#2530)

* unexport as many types and functions from cataloger packages as possible

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

* capture type and signature information in convention test

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

* check that we return pkg.Cataloger from constructors

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

---------

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

syft/pkg/cataloger/python/cataloger.go

@@ -21,7 +21,7 @@ func DefaultCatalogerConfig() CatalogerConfig {
 }
 
 // NewPackageCataloger returns a new cataloger for python packages referenced from poetry lock files, requirements.txt files, and setup.py files.
-func NewPackageCataloger(cfg CatalogerConfig) *generic.Cataloger {
+func NewPackageCataloger(cfg CatalogerConfig) pkg.Cataloger {
 	rqp := newRequirementsParser(cfg)
 	return generic.NewCataloger("python-package-cataloger").
 		WithParserByGlobs(rqp.parseRequirementsTxt, "**/*requirements*.txt").

syft/pkg/cataloger/python/parse_pipfile_lock.go

@@ -29,11 +29,11 @@ type pipfileLock struct {
 			VerifySsl bool   `json:"verify_ssl"`
 		} `json:"sources"`
 	} `json:"_meta"`
-	Default map[string]Dependency `json:"default"`
-	Develop map[string]Dependency `json:"develop"`
+	Default map[string]pipfileLockDependency `json:"default"`
+	Develop map[string]pipfileLockDependency `json:"develop"`
 }
 
-type Dependency struct {
+type pipfileLockDependency struct {
 	Hashes  []string `json:"hashes"`
 	Version string   `json:"version"`
 	Index   string   `json:"index"`