Rename/deprecate into bits to format bits (#14634)

# Description
`into bits` is a bad name because it is not a traditional type cast to a
`bits` type like all the other `into` commands.

Instead it is a pretty printer generating `string` type output. Thus the
correct bucket is `format` and its subcommands.


# User-Facing Changes
`into bits` will raise a `DeprecatedWarning` suggesting the move to
`format bits`
`into bits` can be removed in `0.103.0`

# Tests + Formatting
All tests that relied on `into bits` have been updated to `format bits`

crates/nu-cmd-extra/tests/commands/bits/format.rs

@@ -0,0 +1,13 @@
+use nu_test_support::nu;
+
+#[test]
+fn byte_stream_into_bits() {
+    let result = nu!("[0x[01] 0x[02 03]] | bytes collect | format bits");
+    assert_eq!("00000001 00000010 00000011", result.out);
+}
+
+#[test]
+fn byte_stream_into_bits_is_stream() {
+    let result = nu!("[0x[01] 0x[02 03]] | bytes collect | format bits | describe");
+    assert_eq!("string (stream)", result.out);
+}