feat: update syft license concept to complex struct (#1743)

this PR makes the following changes to update the underlying license model to have more expressive capabilities
it also provides some guarantee's surrounding the license values themselves

- Licenses are updated from string -> pkg.LicenseSet which contain pkg.License with the following fields:
- original `Value` read by syft
- If it's possible to construct licenses will always have a valid SPDX expression for downstream consumption
- the above is run against a generated list of SPDX license ID to try and find the correct ID
- SPDX concluded vs declared is added to the new struct
- URL source for license is added to the new struct
- Location source is added to the new struct to show where the expression was pulled from

go.sum

@@ -207,6 +207,8 @@ github.com/fsnotify/fsnotify v1.6.0/go.mod h1:sl3t1tCWJFWoRz9R8WJCbQihKKwmorjAbS
 github.com/gabriel-vasile/mimetype v1.4.0 h1:Cn9dkdYsMIu56tGho+fqzh7XmvY2YyGU0FnbhiOsEro=
 github.com/gabriel-vasile/mimetype v1.4.0/go.mod h1:fA8fi6KUiG7MgQQ+mEWotXoEOvmxRtOJlERCzSmRvr8=
 github.com/ghodss/yaml v1.0.0/go.mod h1:4dBDuWmgqj2HViK6kFavaiC9ZROes6MMH2rRYeMEF04=
+github.com/github/go-spdx/v2 v2.1.2 h1:p+Tv0yMgcuO0/vnMe9Qh4tmUgYhI6AsLVlakZ/Sx+DM=
+github.com/github/go-spdx/v2 v2.1.2/go.mod h1:hMCrsFgT0QnCwn7G8gxy/MxMpy67WgZrwFeISTn0o6w=
 github.com/glebarez/go-sqlite v1.20.3 h1:89BkqGOXR9oRmG58ZrzgoY/Fhy5x0M+/WV48U5zVrZ4=
 github.com/gliderlabs/ssh v0.3.5 h1:OcaySEmAQJgyYcArR+gGGTHCyE7nvhEMTlYY+Dp8CpY=
 github.com/gliderlabs/ssh v0.3.5/go.mod h1:8XB4KraRrX39qHhT6yxPsHedjA08I/uBVwj4xC+/+z4=