Allow configuring to ignore history entries matching a pattern

Set ZSH_AUTOSUGGEST_HISTORY_IGNORE to a glob pattern to have the history
and match_prev_cmd suggestion strategies never make suggestions matching
that pattern.

For example, set to "cd *" to never suggest any `cd` commands from
history (see issues #340 and #425). Or set to "?(#c50,)" to never
suggest anything 50 characters or longer (see issue #429).

spec/strategies/history_spec.rb

@@ -8,5 +8,16 @@ describe 'the `history` suggestion strategy' do
     end
   end
 
+  context 'when ZSH_AUTOSUGGEST_HISTORY_IGNORE is set to a pattern' do
+    let(:options) { ['ZSH_AUTOSUGGEST_HISTORY_IGNORE="* bar"'] }
+
+    it 'does not make suggestions that match the pattern' do
+      with_history('ls foo', 'ls bar', 'echo baz') do
+        session.send_string('ls')
+        wait_for { session.content }.to eq('ls foo')
+      end
+    end
+  end
+
   include_examples 'special characters'
 end