Add support for fnm (#593)

* add fnm

Signed-off-by: Daniel Sieradski <daniel@self.agency>

* restore path list

---------

Signed-off-by: Daniel Sieradski <daniel@self.agency>

modules/fnm/README.md

@@ -0,0 +1,15 @@
+# Fast Node Manager (fnm)
+
+Enables Nushell support for [Fast Node Manager (fnm)](https://github.com/Schniz/fnm), a fast and simple Node.js version manager. Based on [this GitHub issue](https://github.com/Schniz/fnm/issues/463) and [fnm-nushell](https://github.com/Southclaws/fnm-nushell).
+
+Requires `fnm` to be installed separately.
+
+## Install
+
+Clone this repo or copy the `fnm.nu` file wherever your prefer to keep your Nushell scripts.
+
+Edit your Nushell config file (`$nu.config-path`) and add the line:
+
+```nu
+use /path/to/fnm.nu
+```

modules/fnm/fnm.nu

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+export-env {
+    def fnm-env [] {
+        mut env_vars = {}
+        let pwsh_vars = (^fnm env --shell power-shell)
+        let var_table = ($pwsh_vars
+            | lines
+            | parse "$env:{key} = \"{value}\""
+        )
+        for v in $var_table  {
+            mut value: any = null
+            if ($v.key | str downcase) == 'path' {
+                $value = ($v.value | split row (char esep))
+            } else {
+                $value = $v.value
+            }
+            $env_vars = ($env_vars | insert $v.key $value)
+        }
+        return $env_vars
+    }
+
+    if not (which fnm | is-empty) {
+        fnm-env | load-env
+
+        if (not ($env | default false __fnm_hooked | get __fnm_hooked)) {
+            $env.__fnm_hooked = true
+            $env.config = ($env | default {} config).config
+            $env.config = ($env.config | default {} hooks)
+            $env.config = ($env.config | update hooks ($env.config.hooks | default {} env_change))
+            $env.config = ($env.config | update hooks.env_change ($env.config.hooks.env_change | default [] PWD))
+            $env.config = ($env.config | update hooks.env_change.PWD ($env.config.hooks.env_change.PWD | append { |before, after|
+                if ('FNM_DIR' in $env) and ([.nvmrc .node-version] | path exists | any { |it| $it }) {
+                    (^fnm use); (fnm-env | load-env)
+                }
+            }))
+        }
+    }
+}