Backport of Convert variable types before applying defaults into v1.3

[teamterraform]

Backport

This PR is auto-generated from #32027 to be assessed for backporting due to the inclusion of the label 1.3-backport.

WARNING automatic cherry-pick of commits failed. Commits will require human attention.

The below text is copied from the body of the original PR.

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Fixes #31978

Currently Terraform attempts to apply defaults in variables before calling go-cty to convert the variables into their actual concrete types. This can lead to a situation where HCL cannot apply the defaults because of a type incompatibility and then panics and crashes Terraform (#31978). It's kind of impossible to recover from or predict this situation without modifying the HCL public functions (eg. make the panic return an error, or add a new function like CheckCanApplyDefaults). We can't do this check with go-cty because as far as go-cty is concerned these are perfectly valid conversions. Note, that HCL and go-cty disagree here about what is or what isn't a valid type conversion.

This PR switches the order of these operations. We now go through go-cty to convert to the concrete type first, then when we call the apply defaults function the types are guaranteed to match and HCL doesn't need to worry about any kind of conversions.

This change requires an upstream fix in go-cty, so go-cty is updated as part of this change.

Target Release

1.3.4

Draft CHANGELOG entry

BUG FIXES

• Input and Module Variables: Convert variable types before attempting to apply default values

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