fix "from env" newline handling (#1021)

Many (at least the ones I have encountered) env loaders replace "\n"
with a
literal newline character when loading an env variable. I need this
change in
my personal config and I think others would also prefer this default.

modules/formats/from-env.nu

@@ -6,6 +6,11 @@ def "from env" []: string -> record {
     | split column '#' # remove comments
     | get column1
     | parse "{key}={value}"
-    | str trim value -c '"' # unquote values
+    | update value {
+        str trim -c '"' | # unquote values
+        str replace -a "\\n" "\n" # replace `\n` with newline char
+        str replace -a "\\r" "\r" # replace `\r` with carriage return
+        str replace -a "\\t" "\t" # replace `\t` with tab
+    }
     | transpose -r -d
 }