* Get asdf info BATS tests working
* Create `versions.Installed` function
* Update `versions.Latest` to return single version
* Implement `latest` asdf command
* Implement info command
* Remove duplicate and unneeded BATS tests from `main_test.go`
* remove download dir for plugin when removing plugin
* update plugins.Add function so downloads directory is created
* Create `plugins.New` function, updating existing code to use it
* Add another test for `hook.Run` function
* Enable `plugin_add_command.bats` tests for Go implementation of asdf
* Add `RunCallback` method to `Plugin` struct
* Update `plugins.Add` function to run `post-plugin-add` plugin callback script
* Handle Bash expression and scripts properly in `execute` package so `$@` is always set
* Create `pluginindex.Build` function
* Use `pluginindex` when no plugin URL provided for plugin add command
* Get more `plugin_add_command` BATS tests passing against Golang version
* Only use `pluginindex` when it is not disabled
* Update error message so it matches legacy format
* Add staticcheck.conf
* Simplify BATS test Golang code
* Update plugin add test to new command format
* Correctly set `ASDF_DATA_DIR` for BATS tests
* Rename `PluginAdd` function to `Add`
* Create `plugin.Remove` function
* Make plugin remove command invoke `plugin.Remove` function
* remove underscores from function names (addresses warnings from revive linter)
* create installMockPluginRepo function
* implement plugin list command
