Mulitple improvements of the crawler

1) Set document IDs to avoid duplicating documents;
2) Set the `creationTime` field of each document in the index;
3) set the `values`, `kinds` and `identifiers` fields for all documents;
4) Add a `Copy` method into the `Document` struct: this fixes the issue
where all the documents existing in the index point to the same Document
object;
5) Avoid using keystore redis;
6) Set imagePullPolicy to `Always` for crawler jobs.

api/internal/crawl/crawler/crawler_test.go

@@ -29,7 +29,7 @@ type testCrawler struct {
 }
 
 func (c testCrawler) Match(d *doc.Document) bool {
-	return d != nil && strings.HasPrefix(d.ID(), c.matchPrefix)
+	return d != nil
 }
 
 func (c testCrawler) FetchDocument(_ context.Context, d *doc.Document) error {