Split a FASTA file in chunks

Closes #15 (closed)

tools/utils/split_fasta/example_usage/Snakefile

+configfile: "config.yaml"
+
+def count_sequences(fasta_file):
+    with open(fasta_file, 'r') as file:
+        seq = 0
+        for line in file:
+            if '>' in line:
+                seq += 1
+    return seq
+
+# ==== Snakefile path ====
+__split_fasta_rules = config.get("snakefiles", {}).get("split_fasta")
+
+__main_output_dir = config.get('output_dir', 'output')
+
+# ==== Split FASTA ====
+__split_fasta_output_dir = __main_output_dir +  "/split_fasta"
+
+__split_fasta_input = config['input_fasta']
+__split_fasta_number_sequences = config.get('split_fasta', {}).get('number_sequences', 1000000)
+total_number_sequences = count_sequences(__split_fasta_input)
+EXTENSIONS = [f"{i:05d}" for i in range(0, int(total_number_sequences/__split_fasta_number_sequences) + 1)]
+__split_fasta_prefix = "/".join([__split_fasta_output_dir, config['split_fasta']['prefix']])
+__split_fasta_output = expand(__split_fasta_prefix + "{ext}.fa", ext=EXTENSIONS)
+include: __split_fasta_rules
+
+rule all:
+    input: __split_fasta_output