[Metadata][Processor] Elastic Agent + VMware Metadata

**Describe the enhancement:**
Add a new processor (similar to add_cloud_metadata) to add from virtual stack provider

**Describe a specific use case for the enhancement or feature:**
As a user, we don't have all of our hosts/elastic agent in the cloud, and more metadata driven fields, like which vcenter the host/elastic agent its located in.

**What is the definition of done?**

The inclusion of VMware metadata fields that can help with observability use cases.

Start by reviewing the existing add_cloud_metadata processor as the stated model for a new virtual-stack metadata processor. Define which VMware metadata fields are required for observability and validate that the completed processor includes those fields; the issue does not identify files or tests.

Written by the indexing model from the issue text.