fixup! feat: HashMap and IMap modules with the vocabulary of the FSharp.Core Map module

`yield!` of an array of struct pairs and of a hash map had no null check: a `null` array or map
failed with `NullReferenceException` when the buffer ran, and not as `ArgumentNullException` that
names `pairs` or `table` when the member runs, as the overloads for sequences do. Both members now
call `checkNotNull` first, and the signature file documents the exception.

The other members of `HashMapCE` take a struct (`Yield`), a function value of the expression
(`YieldFrom` of a buffer, `Combine`, `Delay`, `While`, `TryWith`, `TryFinally`, `Using`) or the
sequence that is already checked (`YieldFrom`, `For`), as in `FlatListCE`.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

Author: xperiandri

src/FSharp.Collections.Immutable/HashMap/HashMapCE.fs

@@ -35,6 +35,9 @@ type HashMapCE<'Key when 'Key : not null> (keyComparer : IEqualityComparer<'Key>
                 builder[key] <- value
 
     member inline _.YieldFrom (pairs : struct ('Key * 'Value) array) : HashMapBuffer<'Key, 'Value> =
+        // A null array fails when the buffer runs; the expression rejects it when yield! runs, as it rejects a sequence
+        checkNotNull (nameof pairs) pairs
+
         fun builder ->
             for struct (key, value) in pairs do
                 builder[key] <- value
@@ -47,6 +50,9 @@ type HashMapCE<'Key when 'Key : not null> (keyComparer : IEqualityComparer<'Key>
                 builder[pair.Key] <- pair.Value
 
     member inline _.YieldFrom (table : HashMap<'Key, 'Value>) : HashMapBuffer<'Key, 'Value> =
+        // A null hash map fails when the buffer runs; the expression rejects it when yield! runs, as it rejects a sequence
+        checkNotNull (nameof table) table
+
         fun builder ->
             for pair in table do
                 builder[pair.Key] <- pair.Value

src/FSharp.Collections.Immutable/HashMap/HashMapCE.fsi

@@ -77,6 +77,7 @@ type HashMapCE<'Key when 'Key : not null> =
     /// <summary>
     /// Sets the bindings of an array of struct pairs.
     /// </summary>
+    /// <exception cref="T:System.ArgumentNullException">Thrown when the array is <see langword="null"/>.</exception>
     /// <remarks>
     /// A value that the default comparer of the values finds equal to the value of an earlier binding of the key keeps the
     /// earlier binding, its key included (ADR 0001, D14).
@@ -96,6 +97,7 @@ type HashMapCE<'Key when 'Key : not null> =
     /// <summary>
     /// Sets the bindings of a hash map.
     /// </summary>
+    /// <exception cref="T:System.ArgumentNullException">Thrown when the hash map is <see langword="null"/>.</exception>
     /// <remarks>
     /// A value that the default comparer of the values finds equal to the value of an earlier binding of the key keeps the
     /// earlier binding, its key included (ADR 0001, D14).