Handle BLOB column type in SQLite as binary data (#15681)

* Fixed not handling blob correctly in sqlite
* Fixed setLen commented by mistake
* Added binary example as db_sqlite doc
* Added tests for sqlite binary data

tests/stdlib/tsqlitebindatas.nim

@@ -0,0 +1,50 @@
+discard """
+  action: "run"
+  exitcode: 0
+"""
+import db_sqlite
+import random
+import os
+from stdtest/specialpaths import buildDir
+
+block tsqlitebindatas: ## db_sqlite binary data
+  const dbName = buildDir / "tsqlitebindatas.db"
+
+  let origName = "Bobby"
+  var orig = newSeq[float64](150)
+  randomize()
+  for x in orig.mitems:
+    x = rand(1.0)/10.0
+
+  discard tryRemoveFile(dbName)
+  let db = open(dbName, "", "", "")
+  let createTableStr = sql"""CREATE TABLE test(
+    id INTEGER NOT NULL PRIMARY KEY,
+    name TEXT,
+    data BLOB
+  )
+  """
+  db.exec(createTableStr)
+
+  var dbuf = newSeq[byte](orig.len*sizeof(float64))
+  copyMem(unsafeAddr(dbuf[0]), unsafeAddr(orig[0]), dbuf.len)
+
+  var insertStmt = db.prepare("INSERT INTO test (id, name, data) VALUES (?, ?, ?)")
+  insertStmt.bindParams(1, origName, dbuf)
+  let bres = db.tryExec(insertStmt)
+  doAssert(bres)
+
+  finalize(insertStmt)
+
+  var nameTest = db.getValue(sql"SELECT name FROM test WHERE id = ?", 1)
+  doAssert nameTest == origName
+
+  var dataTest = db.getValue(sql"SELECT data FROM test WHERE id = ?", 1)
+  let seqSize = int(dataTest.len*sizeof(byte)/sizeof(float64))
+  var res: seq[float64] = newSeq[float64](seqSize)
+  copyMem(unsafeAddr(res[0]), addr(dataTest[0]), dataTest.len)
+  doAssert res.len == orig.len
+  doAssert res == orig
+
+  db.close()
+  doAssert tryRemoveFile(dbName)