Partial removal of circular dependencies between spack and llnl (#40090)

Modifications:
- [x] Move `spack.util.string` to `llnl.string`
- [x] Remove dependency of `llnl` on `spack.error`
- [x] Move path of `spack.util.path` to `llnl.path`
- [x] Move `spack.util.environment.get_host_*` to `spack.spec`

lib/spack/llnl/util/lock.py

@@ -14,7 +14,7 @@
 
 from llnl.util import lang, tty
 
-import spack.util.string
+from ..string import plural
 
 if sys.platform != "win32":
     import fcntl
@@ -169,7 +169,7 @@ def _attempts_str(wait_time, nattempts):
     if nattempts <= 1:
         return ""
 
-    attempts = spack.util.string.plural(nattempts, "attempt")
+    attempts = plural(nattempts, "attempt")
     return " after {} and {}".format(lang.pretty_seconds(wait_time), attempts)