`dunai-examples`: Convert examples from SDL1 to SDL2

[ivanperez-keera]

SDL 1 is deprecated. It seems to no longer compile well with modern versions of GHC.

Porting the examples to SDL 2 would make them more relevant to current developers, and keep our CI infrastructure working well.

[ivanperez-keera]

Help is sought for this. There are four modules that use SDL:

dunai-examples/bouncingball/BouncingBall.hs
dunai-examples/classicfrp/GTest.hs
dunai-examples/classicfrp/Test.hs
dunai-examples/list/BouncingBall.hs

If someone is able to work on this, please do the following:

• Send a PR that references this issue.
• Add one commit to upgrade each of the examples. Make sure each of those commits updates both the Haskell code and the corresponding cabal file.
• For each commit, add the following commit message, adjusting to the example you are modifying:

dunai-examples: Upgrade example to use SDL2. Refs #446.

SDL 1 is deprecated, and no longer maintained. To keep the example
working with more modern versions of packages in the Haskell ecosystem,
this commit ports <NAME_OF_EXAMPLE> to use SDL2.