Catalog available Charts and cache them globally

Summary

This MR adds a utility to populate and query the available Charts. It provides a global catalog to access the Charts across the controller.

Usage

1. Populate the global Chart catalog when the process starts, e.g. in main function:

   charts.PopulateGlobalCatalog(
       charts.WithSearchPath("/path/to/helm/charts", "/another/path"),
       charts.WithFilePattern("*.tgz", "*.tar.gz"),
       charts.WithLogger(logger))

2. Lookup Charts when needed:

   chart := charts.GlobalCatalog().Query(
     charts.WithName("gitlab"),
     charts.WithVersion(adapter.ChartVersion()).First()
   
   if chart == nil {
       return errors.Errorf("Chart version %s is not available, use one of %s",
           adapter.Version(), charts.GlobalCatalog().Versions("gitlab"))
   }

Bells and whistles

• The catalog may contain different versions of multiple Charts. It uses the combination of Chart name and version to distinguish between different Charts.

• The new population method can:

  • search Charts multiple paths
  • search directories recursively
  • retrieve Charts both from directories and archive files
  • use multiple file name patterns

• The catalog query can:

  • list available Chart names, versions, and appVersions
  • select Charts with a combination of criteria on name, version, and appVersion.

Related issues

This is related to #579 (closed) but it does not close it just yet.

The application of the utility that is provided in this MR can be done in a separate MR to avoid over-complicating it.