Support for validate the whole hub manifest

[mkuziemko]

Description

Changes proposed in this pull request:

• add a possibility to validate all files from a directory
• add a possibility to validate all files from a directory and subdirectories (recursive)

Testing

1. Checkout this branch and build CLI:

   gh pr checkout 574

   make build-tool-cli

2. Clone hub-manifests repo:

   gh repo clone capactio/hub-manifests

3. Execute manifest validate:

   capact manifest validate {HUB_MANIFEST_REPO_PATH}/manifests/ -r 

All files from catalog manifests and subdirectories should be validated. Execute the same command but without -r should validate 0 files. (as there is no file in that directory)

Related issue(s)

Resolves #346