Add the Ocaml ecosystem (#3112)

Signed-off-by: Laurent Goderre <laurent.goderre@docker.com>

syft/pkg/type.go

@@ -43,6 +43,7 @@ const (
 	RustPkg                 Type = "rust-crate"
 	SwiftPkg                Type = "swift"
 	SwiplPackPkg            Type = "swiplpack"
+	OpamPkg                 Type = "opam"
 	WordpressPluginPkg      Type = "wordpress-plugin"
 )
 
@@ -80,12 +81,13 @@ var AllPkgs = []Type{
 	RustPkg,
 	SwiftPkg,
 	SwiplPackPkg,
+	OpamPkg,
 	WordpressPluginPkg,
 }
 
 // PackageURLType returns the PURL package type for the current package.
 //
-//nolint:funlen
+//nolint:funlen, gocyclo
 func (t Type) PackageURLType() string {
 	switch t {
 	case AlpmPkg:
@@ -145,6 +147,8 @@ func (t Type) PackageURLType() string {
 		return packageurl.TypeSwift
 	case SwiplPackPkg:
 		return "swiplpack"
+	case OpamPkg:
+		return "opam"
 	case WordpressPluginPkg:
 		return "wordpress-plugin"
 	default:
@@ -223,6 +227,8 @@ func TypeByName(name string) Type {
 		return SwiftPkg
 	case "swiplpack":
 		return SwiplPackPkg
+	case "opam":
+		return OpamPkg
 	case "wordpress-plugin":
 		return WordpressPluginPkg
 	default: