properly expose AcquireByHash through the api

- new publish calls can now enable AcquireByHash by right away (previously
  one would have had to create a new publishing endpoint and then
  explicitly switch it to AcquireByHash)
- all json marshals of PublishedRepo now contain AcquireByHash (allows
  inspecting if a given endpoint has AcquireByHash enabled already; also
  enables verification that a switch/update actually applied a
  potential AcquireByHash change
- update all tests to reflect that default state of AcquireByHash
- update creation and switch testing to explicitly toggle AcquireByHash to
  make sure state mutation works as expected

api/publish.go

@@ -104,6 +104,7 @@ func apiPublishRepoOrSnapshot(c *gin.Context) {
 		SkipContents         *bool
 		Architectures        []string
 		Signing              SigningOptions
+		AcquireByHash        *bool
 	}
 
 	if c.Bind(&b) != nil {
@@ -201,6 +202,10 @@ func apiPublishRepoOrSnapshot(c *gin.Context) {
 		published.SkipContents = *b.SkipContents
 	}
 
+	if b.AcquireByHash != nil {
+		published.AcquireByHash = *b.AcquireByHash
+	}
+
 	duplicate := collection.CheckDuplicate(published)
 	if duplicate != nil {
 		context.CollectionFactory().PublishedRepoCollection().LoadComplete(duplicate, context.CollectionFactory())