Add input to set version code

Use action input `androidVersionCode` when provided. Generate the androidVersionCode from the version otherwise.

src/model/android-versioning.test.js

@@ -0,0 +1,27 @@
+import AndroidVersioning from './android-versioning';
+
+describe('Android Versioning', () => {
+  describe('versionToVersionCode', () => {
+    it('defaults to 1 when version is not a valid semver', () => {
+      expect(AndroidVersioning.versionToVersionCode('abcd')).toBe(1);
+    });
+
+    it('returns a number', () => {
+      expect(AndroidVersioning.versionToVersionCode('123.456.789')).toBe(123456789);
+    });
+
+    it('throw when generated version code is too large', () => {
+      expect(() => AndroidVersioning.versionToVersionCode('1234.0.0')).toThrow();
+    });
+  });
+
+  describe('determineVersionCode', () => {
+    it('defaults to parsed version', () => {
+      expect(AndroidVersioning.determineVersionCode('1.2.3', '')).toBe(1002003);
+    });
+
+    it('use specified code', () => {
+      expect(AndroidVersioning.determineVersionCode('1.2.3', 2)).toBe(2);
+    });
+  });
+});