test: move all module tests to the test/ directory

test/ds/numbers.c

@@ -0,0 +1,11 @@
+#include <blue/ds/number.h>
+#include <stdio.h>
+
+int main(void)
+{
+	b_number *number = b_number_create_float(6.8);
+
+	printf("number=%zd\n", B_NUMBER_IVAL(number));
+	b_number_unref(number);
+	return 0;
+}