chore(src): Move all source files to src directory

hgit.cabal

package.yaml

src/Data/Git.hs

src/Data/Git/Config.hs

src/Data/Git/Delta.hs

src/Data/Git/Diff.hs

src/Data/Git/Diff/Patience.hs

src/Data/Git/Imports.hs

src/Data/Git/Index.hs

src/Data/Git/Internal.hs

src/Data/Git/Monad.hs

src/Data/Git/Named.hs

src/Data/Git/OS.hs

src/Data/Git/Parser.hs

src/Data/Git/Path.hs

src/Data/Git/Ref.hs

src/Data/Git/Repository.hs

src/Data/Git/Revision.hs

src/Data/Git/Storage.hs

src/Data/Git/Storage/CacheFile.hs