Add SetAccountCurrency() override (#7284)

* Add SetAccountCurrency overload

- Add SetAccountCurrencyOverload to allow the user to set also account
  currency quantity
- Add regression and unit tests to cover the changes

* Add regression algos

* Simplifiy SetAccountCurrency implementation

* Minor changes

* Minor changes

Algorithm.Python/BasicSetAccountCurrencyWithAmountAlgorithm.py

@@ -0,0 +1,23 @@
+# QUANTCONNECT.COM - Democratizing Finance, Empowering Individuals.
+# Lean Algorithmic Trading Engine v2.0. Copyright 2014 QuantConnect Corporation.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from AlgorithmImports import *
+from BasicSetAccountCurrencyAlgorithm import BasicSetAccountCurrencyAlgorithm
+
+### <summary>
+### Basic algorithm using SetAccountCurrency with an amount
+### </summary>
+class BasicSetAccountCurrencyWithAmountAlgortihm(BasicSetAccountCurrencyAlgorithm):
+    def SetAccountCurrencyAndAmount(self):
+        # Before setting any cash or adding a Security call SetAccountCurrency
+        self.SetAccountCurrency("EUR", 200000)