js -d:nodejs now supports osenv: getEnv, putEnv, envPairs, delEnv, existsEnv (v2) (#15826)

* js -d:nodejs now supports osenv: `getEnv`, `putEnv`, `envPairs`, `delEnv`, `existsEnv`

* refactor to osenv

* fix for js (without -d:nodejs) + VM

Co-authored-by: Andreas Rumpf <rumpf_a@web.de>

tests/js/tos.nim

@@ -19,3 +19,29 @@ block:
   if not isWindows:
     doAssert cwd.isAbsolute
     doAssert relativePath(getCurrentDir() / "foo", "bar") == "../foo"
+
+import std/sequtils
+
+template main =
+  putEnv("foo", "bar")
+  doAssert getEnv("foo") == "bar"
+  doAssert existsEnv("foo")
+
+  putEnv("foo", "")
+  doAssert existsEnv("foo")
+  putEnv("foo", "bar2")
+  doAssert getEnv("foo") == "bar2"
+
+  when nimvm:
+    discard
+  else:
+    # need support in vmops: envPairs, delEnv
+    let s = toSeq(envPairs())
+    doAssert ("foo", "bar2") in s
+    doAssert ("foo", "bar") notin s
+
+    delEnv("foo")
+    doAssert not existsEnv("foo")
+
+static: main()
+main()