Configure go-plugin's `SecureConfig`

[wata727]

The SecureConfig is a mechanism for verifying checksums at runtime, provided by go-plugin.
https://pkg.go.dev/github.com/hashicorp/go-plugin@v1.4.5#SecureConfig

To make use of this, we first need to save the checksum of plugins. It's probably a good idea to first introduce a dependency lockfile. See also terraform-linters/tflint#1486

[fgm]

Just to be clear, is this something that has to be done by TFLint plugin maintainers ? or TF providers ? or config authors ?

AIUI, it's the first one, but just want to be sure.

[wata727]

This feature will be enabled automatically in future Plugin SDK updates.
Plugin developers should use the latest SDK to enable this feature. End users simply update to plugins built with the latest SDK.