Changes from 3.0.0 to 3.0.1

• Add BLOSC_DEPENDENCY_MODE to choose BUNDLED, EXTERNAL, or AUTO
  dependency resolution, defaulting to BUNDLED for compatibility.

• Add BLOSC_ENABLE_ZFP to make ZFP optional in external builds while
  still allowing users to require or disable it explicitly.

• Add external ZFP discovery and improve LZ4/Zstd find modules so
  external builds provide proper imported targets and include dirs.

• Avoid dependency CMake variables polluting the Blosc2 package install
  dir, and install Blosc2 config files under the expected Blosc2 path.

• Document the new options for distro packagers.