Co-authored-by: Tu Nguyen <im2nguyen@users.noreply.github.com>

Co-authored-by: Tu Nguyen <im2nguyen@users.noreply.github.com>

Co-authored-by: Tu Nguyen <im2nguyen@users.noreply.github.com>

Co-authored-by: Tu Nguyen <im2nguyen@users.noreply.github.com>

New marks.Sensitive type, and audit of sensitive marks usage

Make sure sensitivity checks are looking for specific marks rather than
any marks at all.

marks.Sensitive

* terraform: use hcl.MergeBodies instead of configs.MergeBodies for provider configuration

Previously, Terraform would return an error if the user supplied provider configuration via interactive input iff the configuration provided on the command line was missing any required attributes - even if those attributes were already set in config.

That error came from configs.MergeBody, which was designed for overriding valid configuration. It expects that the first ("base") body has all required attributes. However in the case of interactive input for provider configuration, it is perfectly valid if either or both bodies are missing required attributes, as long as the final body has all required attributes. hcl.MergeBodies works very similarly to configs.MergeBodies, with a key difference being that it only checks that all required attributes are present after the two bodies are merged.

I've updated the existing test to use interactive input vars and a schema with all required attributes. This test failed before switching from configs.MergeBodies to hcl.MergeBodies.

* add a command package test that shows that we can still have providers with dynamic configuration + required + interactive input merging

This test failed when buildProviderConfig still used configs.MergeBodies instead of hcl.MergeBodies

The -var command line option comes with the disadvantage that a user must
contend both with Terraform's own parser and with the parser in whichever
shell they've decided to use, and different shells on different platforms
have different rules.

Previously we've largely just assumed that folks know the appropriate
syntax for the shell they chose, but it seems that command lines involving
spaces and other special characters arise rarely enough in other commands
that Terraform is often the first time someone needs to learn the
appropriate syntax for their shell.

We can't possibly capture all of the details of all shells in our docs,
because that's far outside of our own scope, but hopefully this new
section will go some way to give some real examples that will help folks
figure out how to write suitable escape sequences, if they choose to
set complex variable values on the command line rather than in .tfvars
as we recommend elsewhere on this page.

Add links to terraform versions tutorials

Upgrade cty to v1.8.4

This PR adds decoding for the upcoming "moved" blocks in configuration. This code is gated behind an experiment called EverythingIsAPlan, but the experiment is not registered as an active experiment, so it will never run (there is a test in place which will fail if the experiment is ever registered).

This also adds a new function to the Targetable interface, AddrType, to simplifying comparing two addrs.Targetable.

There is some validation missing still: this does not (yet) descend into resources to see if the actual resource types are the same (I've put this off in part because we will eventually need the provider schema to verify aliased resources, so I suspect this validation will have to happen later on).

* docs: Document naming conventions for templates & backend configs

* Update website/docs/cli/config/config-file.html.md
Co-authored-by: Alisdair McDiarmid <alisdair@users.noreply.github.com>

* Update website/docs/language/functions/templatefile.html.md
Co-authored-by: Alisdair McDiarmid <alisdair@users.noreply.github.com>
Co-authored-by: Alisdair McDiarmid <alisdair@users.noreply.github.com>

json-output: Omit unchanged resource_drift entries

blocktoattr fixup dropping MissingItemRange

When blocktoattr.fixupBody returned its content, the value for
`MissingItemRange` was omitted, losing the diagnostic Subject.

Previously, if any resources were found to have drifted, the JSON plan
output would include a drift entry for every resource in state. This
commit aligns the JSON plan output with the CLI UI, and only includes
those resources where the old value does not equal the new value---i.e.
drift has been detected.

Also fixes a bug where the "address" field was missing from the drift
output, and adds some test coverage.

* command: new command, terraform add, generates resource templates

terraform add ADDRESS generates a resource configuration template with all required (and optionally optional) attributes set to null. This can optionally also pre-populate nonsesitive attributes with values from an existing resource of the same type in state (sensitive vals will be populated with null and a comment indicating sensitivity)

* website: terraform add documentation