Support changing the version file for terraform and opentofu

[hinricht]

Describe the bug

Right now, mise with the plugins terraform or opentofu will correctly parse the tool version from the
required_version directive in the main.tf / main.tofu file.
Both plugins support env vars to change the name of the file to parse (ASDF_HASHICORP_TERRAFORM_VERSION_FILE / ASDF_OPENTOFU_VERSION_FILE) (see i.e. https://github.com/asdf-community/asdf-hashicorp?tab=readme-ov-file#usage):

ASDF_HASHICORP_TERRAFORM_VERSION_FILE: Which .tf-file to examine for version constraints when using the legacy_version_file option in ~/.asdfrc. Defaults to main.tf

But when setting this env var to an existing file containing a required_version directive, mise doesn't parse this file.

To Reproduce

$ mkdir test
mise terraform@1.5.0 
$ cd test 
mise terraform@1.5.0
$ echo -e "terraform {\n  required_version = \"1.7.1\" \n}" > main.tf
mise terraform@1.7.1   
$ mise config         
Path                       Plugins            
/tmp/test/main.tf          terraform          
~/.config/mise/config.toml opentofu, terraform
mise terraform@1.7.1  

$ mv main.tf versions.tf
mise terraform@1.5.0  
$ export ASDF_HASHICORP_TERRAFORM_VERSION_FILE=versions.tf
mise terraform@1.5.0                                                                
/tmp/test $ mise config                                             
Path                       Plugins            
~/.config/mise/config.toml opentofu, terraform
mise terraform@1.5.0 

Expected behavior

When I export ASDF_HASHICORP_TERRAFORM_VERSION_FILE=versions.tf and have a versions.tf file with a required_version directive, mise should pin the terraform/tofu version to this version.

mise doctor output

version: 2024.9.5 linux-x64 (1f0f03e 2024-09-17)
activated: yes
shims_on_path: yes

build_info: 
  Target: x86_64-unknown-linux-gnu
  Features: DEFAULT, NATIVE_TLS, OPENSSL
  Built: Tue, 17 Sep 2024 13:42:22 +0000
  Rust Version: rustc 1.81.0 (eeb90cda1 2024-09-04)
  Profile: release

shell: 
  /usr/bin/zsh
  zsh 5.9 (x86_64-pc-linux-gnu)

dirs: 
  data: ~/.local/share/mise
  config: ~/.config/mise
  cache: ~/.cache/mise
  state: ~/.local/state/mise
  shims: ~/.local/share/mise/shims

config_files: 
  ~/.config/mise/config.toml

backends: 
  cargo
  core
  go
  npm
  pipx
  spm
  ubi
  vfox

plugins: 
  terraform  https://github.com/asdf-community/asdf-hashicorp.git#22eb1c4

toolset: 
  terraform@1.5.0  

env_vars: 
  MISE_SHELL=zsh

settings: 
  activate_aggressive = false
  all_compile = false
  always_keep_download = false
  always_keep_install = false
  asdf = true
  asdf_compat = false
  cargo_binstall = true
  color = true
  disable_default_shorthands = false
  disable_hints = []
  disable_tools = ["opentofu"]
  experimental = true
  go_default_packages_file = "~/.default-go-packages"
  go_download_mirror = "https://dl.google.com/go"
  go_repo = "https://github.com/golang/go"
  go_set_gopath = false
  go_set_goroot = true
  go_skip_checksum = false
  http_timeout = 30
  jobs = 4
  legacy_version_file = true
  legacy_version_file_disable_tools = []
  libgit2 = true
  node_compile = false
  not_found_auto_install = true
  paranoid = false
  pipx_uvx = false
  plugin_autoupdate_last_check_duration = "7d"
  python_default_packages_file = "~/.default-python-packages"
  python_pyenv_repo = "https://github.com/pyenv/pyenv.git"
  raw = false
  trusted_config_paths = []
  quiet = false
  use_versions_host = true
  verbose = false
  vfox = false
  yes = false
  ci = false
  debug = false
  trace = false
  log_level = "info"
  python_venv_auto_create = false

  [status]
  missing_tools = "if_other_versions_installed"
  show_env = false
  show_tools = true

No warnings found