required_version should have higher priority than the tenv default

[giner]

Reading documentation made me realize that required_version is considered by tenv which could have been very useful as we wouldn't have to manage version files (like .tofu-version, tool-version, etc). However, to my surprise, required_version does not work in 99% of cases and the reason is that in all these cases tenv has the default version of a tool set. Wouldn't it make sense consider required_version over the default and use the default and then the latest as the last resort instead? I.e.

Now:

• TOFUENV_TOFU_VERSION environment variable
• .opentofu-version file
• .tool-versions file
• terraform_version_constraint from terragrunt.hcl file
• terraform_version_constraint from terragrunt.hcl.json file
• TOFUENV_TOFU_DEFAULT_VERSION environment variable
• ${TENV_ROOT}/OpenTofu/version file (can be written with tenv tofu use)
• latest-allowed

Proposed:

• TOFUENV_TOFU_VERSION environment variable
• .opentofu-version file
• .tool-versions file
• terraform_version_constraint from terragrunt.hcl file
• terraform_version_constraint from terragrunt.hcl.json file
• latest-allowed (from required_version)
• TOFUENV_TOFU_DEFAULT_VERSION environment variable
• ${TENV_ROOT}/OpenTofu/version file (can be written with tenv tofu use)
• latest

See the resolution order for opentofu here as an example https://github.com/tofuutils/tenv?tab=readme-ov-file#project-binaries