Batch loader to better support laoding of multiple home units at once

[soulomoon]

Originates from haskell/haskell-language-server#4381
Batch loading api is needed for performance.
I assume something like this:

loadCradles ::  [FilePath] -> IO [(Cradle Void, [FilePath])]
-- CradleAction
runCradleMultiFiles :: [FilePath] -> LoadStyle -> IO (CradleLoadResult ComponentOptionsMultiResult)

[soulomoon]

The current status for a single file:

1. find the cradle location for a file.
2. load hie.yaml or implicit one as cradle config.
3. resolve cradle config for the file to get theCradle. (Only here we know what build tools are used for the file)
4. runCradle to run the cradleAction in Cradle and obtain the argumentsghc needed to compile the file

Since only cabal cradle can do batch load. (Multiple cabal files?)
To minimize changes need to be made, internal changes need to be made to cabalActions.
Because we need to merge multiple cabalAction. Current implementation is not possible.

Then the batch load workflow can be:

• For each file
  • find the cradle location
  • load the hie.yaml to cradle config
  • resolve to get Cradle for the file.
• Merge the Cabal cradles, leave others.
• runCradle for each batch of files

[soulomoon]

loadStyle already fullfill batch load all the modules for a single cradle project. closing it