Consul validate misses typo in path to TLS certificates in configuration file that prevents start

#### Overview of the Issue

`consul validate` returns valid if typo in path to TLS cert file location but consul will fail to start when it can't find the cert file

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#### Reproduction Steps

Steps to reproduce this issue, eg:

- Create a config file with the TLS stanza and the standard TLS cert paths to the .pem files.
- Insert a typo into one of the file paths
- Run `consul validate` -> It will return valid (assuming no other problems in the config file!)
- Attempt to start consul -> It will fail and with no useful error message at that!

### Operating system and Environment details

consul 2.0.3+ent on RHEL 9.7 x86_64 VM on nutanix hypervisor

Start by reproducing the issue with a Consul configuration containing a typo in a TLS certificate path, then trace how `consul validate` handles the TLS stanza versus startup. Identify where the missing certificate is accepted and make completion mean validation rejects the bad path with a useful error; verify both the reproduction and a valid configuration.

Written by the indexing model from the issue text.