⚠️ Update Fact API to use qualified keys (source:fact)

[mansam]

Get/replace/delete an anonymous fact
GET/PUT/DELETE /application/1/facts/myfact

Get/replace/delete a qualified fact
GET/PUT/DELETE /application/1/facts/mysource:myotherfact

List and replace for anonymous source:
GET/PUT /application/1/facts

List and replace all by source
GET/PUT /application/1/facts/mysource:

[jortel]

This is fine but generally we have been doing this in other places to reduce the raw sql.

db = h.DB(ctx)
db = db.Where("ApplicationID", id)
db = db.Where("Source", source)
db = db.Where("Key", key)

[jortel]

Might be good to explain how facts are qualified in the description of each endpoint.

[jortel]

Since the model is being fetched (and it's super small), seems like it would be simpler to:

m := &model.Fact{}
db.First(m)
m.Value = f.Value
db.Save(m)

[jortel]

I wonder if it would be good to codify the fact key format as an object to be shared by the api, binding, and addon packages. Though, could be overkill.

Something like:

type FactKey string

func (r *FactKey) With(source, name string) {
   *r = FactKey(
      strings.Join(
         []string{source, name},
         ":"))
}

func (r *FactKey) Source() (s string) {
   if x, _, found := strings.Cut(string(*r), ":"); found {
      s = x
   }
   return
}

func (r *FactKey) Name() (n string) {
   if _, x, found := strings.Cut(string(*r), ":"); found {
      n = x
   } else {
      n = string(*r)

func TestFactKey(t *testing.T) {
   g := gomega.NewGomegaWithT(t)

   key := FactKey("key")
   g.Expect(key.Source()).To(gomega.Equal(""))
   g.Expect(key.Name()).To(gomega.Equal("key"))

   key = FactKey("test:key")
   g.Expect(key.Source()).To(gomega.Equal("test"))
   g.Expect(key.Name()).To(gomega.Equal("key"))

   key = FactKey("")
   key.With("test", "key")
   g.Expect(key.Source()).To(gomega.Equal("test"))
   g.Expect(key.Name()).To(gomega.Equal("key"))
}

[jortel]

After seeing the usage here, I wonder if key.Qualify(source) would be more useful then With(source, name)?
Would result in usages like:

key := api.FactKey("")
key.Qualify(h.source)

And

key := api.FactKey(name)
key.Qualify(h.source)

[jortel]

Looks great.

[jortel]

What if one of the keys in the map is qualified?
Should k be scrubbed through FactKey?