feat: add vault_license_reporting var to opt out of automated license utilization reporting

[in0rdr]

This adds a variable vault_license_reporting to allow enterprise customers to opt out of the automated license utilization reporting.

The default for the variable is false, which means that no config changes are made and the license utilization is reported to HashiCorp automatically.

If the user sets the value to true, the license reporting is disabled in the main configuration file with the reporting stanza:

reporting {
    license {
        enabled = false
   }
}

Setting the value to true on Vault releases which do not yet support the reporting feature results in a warning in the Vault server log.

[in0rdr]

I just noticed that we could probably achieve the same configuration by using the vault_custom_configuration value. However, adding the feature flag for this opt out is more explicit.