[backport] Fix spelling typos (#12755)

compiler/liftdestructors.nim

@@ -477,7 +477,7 @@ proc ownedRefOp(c: var TLiftCtx; t: PType; body, x, y: PNode) =
 
 proc closureOp(c: var TLiftCtx; t: PType; body, x, y: PNode) =
   if c.kind == attachedDeepCopy:
-    # a big problem is that we don't know the enviroment's type here, so we
+    # a big problem is that we don't know the environment's type here, so we
     # have to go through some indirection; we delegate this to the codegen:
     let call = newNodeI(nkCall, c.info, 2)
     call.typ = t

compiler/semcall.nim

@@ -304,7 +304,7 @@ proc getMsgDiagnostic(c: PContext, flags: TExprFlags, n, f: PNode): string =
       # in a concept, eg:
       #   ExplainedConcept {.explain.} = concept x
       #     x.foo is int
-      # We coudl use: `(c.config $ n.sons[1].info)` to get more context.
+      # We could use: `(c.config $ n.sons[1].info)` to get more context.
       discard
     else:
       typeHint = " for type " & getProcHeader(c.config, sym)