Embed frags in sql interpolator

[AugustNagro]

A solution to #34

[EvgenyAfanasev]

What about improving the test by inserting frag in the middle of the query ?

  test("embed Frag into Frag"):
    def findPersonCnt(
        filter: Frag,
        limit: Long = 1,
        offset: Long = 0
    )(using DbCon): Int =
      sql"SELECT count(*) FROM person WHERE $filter LIMIT $limit OFFSET $offset"
        .query[Int]
        .run()
        .head
    val isAdminFrag = sql"is_admin = true"
    connect(ds()):
      val johnCnt = findPersonCnt(sql"first_name = 'John' AND $isAdminFrag", 2)
      assertEquals(johnCnt, 2)

[AugustNagro]

Good suggestion; please review @EvgenyAfanasev and I will merge when you approve.

[EvgenyAfanasev]

Good suggestion; please review @EvgenyAfanasev and I will merge when you approve.

Thank you ! LGTM