Consul Validate for more than just an agent or server configuration

#### Feature Description

Currently, `consul validate` will only validate a config file used by the consul agent, such as a client or server configuration.

The request is to extend this to *any* consul configuration file, such as an intentions configuration, terminating gateway, proxy-defaults etc.

#### Use Case(s)

This feature would come in handy to validate these configuration files for sanity checking, *especially* when submitting config updates that you save in VCS, allowing a pull request test in CICD to run the validate command against them, and verify they're proper, or for an admin doing some local sanity checks prior to a push, to validate them.