Refactor kmer index to disk-based partitioning with minimizer

Refactor kmer index package to use disk-based partitioning with minimizer

- Replace roaring64 bitmaps with disk-based kmer index
- Implement partitioned kmer sets with delta-varint encoding
- Add support for frequency filtering during construction
- Introduce new builder pattern for index construction
- Add streaming operations for set operations (union, intersect, etc.)
- Add support for super-kmer encoding during construction
- Update command line tool to use new index format
- Remove dependency on roaring bitmap library

This change introduces a new architecture for kmer indexing that is more memory efficient and scalable for large datasets.

cmd/obitools/obikindex/main.go

@@ -0,0 +1,23 @@
+package main
+
+import (
+	"os"
+
+	"git.metabarcoding.org/obitools/obitools4/obitools4/pkg/obioptions"
+	"git.metabarcoding.org/obitools/obitools4/obitools4/pkg/obitools/obiconvert"
+	"git.metabarcoding.org/obitools/obitools4/obitools4/pkg/obitools/obikindex"
+)
+
+func main() {
+	optionParser := obioptions.GenerateOptionParser(
+		"obikindex",
+		"builds a roaring kmer index from sequence files",
+		obikindex.OptionSet)
+
+	_, args := optionParser(os.Args)
+
+	sequences, err := obiconvert.CLIReadBioSequences(args...)
+	obiconvert.OpenSequenceDataErrorMessage(args, err)
+
+	obikindex.CLIBuildKmerIndex(sequences)
+}