[WIP] monadless for doobie's ConnectionIO

[szimano]

New feature.

Problem

This is a monadless instance for a popular pure DB connector doobie https://github.com/tpolecat/doobie

Solution

Wrote MonadlessConnectionIO

Notes

One thing i could not find reasons for is:

I've copied tests from the monix.Task monadless instance and with the rescue test originally I had it as

"rescue" - {
    "success" in
      runLiftTest(1) {
        try unlift(one)
        catch {
          case e: Throwable => unlift(two)
        }
      }
    "failure" in
      runLiftTest(1337) {
        try fail[Int]
        catch {
          case e: Exception => unlift(queryInt(1337))
        }
      }
  }

And this never called rescue in failure. Chanigng it to

"rescue" - {
    "success" in
      runLiftTest(1) {
        try unlift(one)
        catch {
          case e: Throwable => unlift(two)
        }
      }
    "failure" in
      runLiftTest(1337) {
        try unlift(two) / fail[Int]
        catch {
          case e: Exception => unlift(queryInt(1337))
        }
      }
  }

Calls rescue properly and makes the code pass.

What am I missing here? Marking the code as WIP for that reason. Otherwise i have it in my production code and it works well.

Checklist

• Unit test all changes
• Update README.md if applicable
• Add [WIP] to the pull request title if it's work in progress
• Squash commits that aren't meaningful changes
• Run sbt scalariformFormat test:scalariformFormat to make sure that the source files are formatted