[Fix] nvm_alias, nvm_version_path: reject .. path components

`nvm_alias` concatenated the requested name onto `$NVM_DIR/alias` and read whatever that resolved to,
so a name with a `..` component escaped the alias dir
- under the default layout, `../../.npmrc` reaches `$HOME/.npmrc`.
`nvm_print_alias_file` echoes every non-comment line of what it opens,
and `nvm use` reports the first one in its "is not yet installed" error,
so an untrusted `.nvmrc` could disclose any file the invoking user can read.

The write side already rejected `..` in an alias name (9275c5ba);
apply the same check on the read side, and to `nvm_version_path`,
which composes a version into a path with no check of its own.

Slashes stay legal, since `lts/iron` and the `lts/*` alias file depend on them.

nvm.sh

@@ -800,6 +800,12 @@ nvm_alias_path() {
 nvm_version_path() {
   local VERSION
   VERSION="${1-}"
+  case "/${VERSION}/" in
+    */../*)
+      nvm_err "invalid version: ${VERSION}"
+      return 3
+    ;;
+  esac
   if [ -z "${VERSION}" ]; then
     nvm_err 'version is required'
     return 3
@@ -1498,6 +1504,15 @@ nvm_alias() {
     return 2
   fi
 
+  # slashes are legal (eg `lts/iron`), but a `..` component would read outside
+  # the alias dir; `nvm_make_alias` rejects the same shape on the write side
+  case "/${ALIAS}/" in
+    */../*)
+      nvm_err "invalid alias name: ${ALIAS}"
+      return 3
+    ;;
+  esac
+
   local NVM_ALIAS_PATH
   NVM_ALIAS_PATH="$(nvm_alias_path)/${ALIAS}"
   if [ ! -f "${NVM_ALIAS_PATH}" ]; then