Add workflow for running solidity unit tests

.github/workflows/run-sut.yml

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+
+name: Running Solidity Unit Tests
+on: [push]
+
+jobs:
+  run_sol_contracts_job:
+    runs-on: ubuntu-latest
+    name: A job to run solidity unit tests on github actions CI
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+      - name: Environment Setup
+        uses: actions/setup-node@v3
+        with:
+          node-version: 14.17.6
+      - name: Run SUT Action
+        uses: EthereumRemix/sol-test@v1
+        with:
+          test-path: 'apps/remix-ide/contracts/tests'
+          compiler-version: '0.8.15'

apps/remix-ide/contracts/tests/Ballot_test.sol

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+// SPDX-License-Identifier: GPL-3.0
+
+pragma solidity >=0.7.0 <0.9.0;
+import "remix_tests.sol"; // this import is automatically injected by Remix.
+import "hardhat/console.sol";
+import "../ballot.sol";
+
+contract BallotTest {
+
+    bytes32[] proposalNames;
+
+    Ballot ballotToTest;
+    function beforeAll () public {
+        proposalNames.push(bytes32("candidate1"));
+        ballotToTest = new Ballot(proposalNames);
+    }
+
+    function checkWinningProposal () public {
+        console.log("Running checkWinningProposal");
+        ballotToTest.vote(0);
+        Assert.equal(ballotToTest.winningProposal(), uint(0), "proposal at index 0 should be the winning proposal");
+        Assert.equal(ballotToTest.winnerName(), bytes32("candidate1"), "candidate1 should be the winner name");
+    }
+
+    function checkWinninProposalWithReturnValue () public view returns (bool) {
+        return ballotToTest.winningProposal() == 0;
+    }
+}