chore(release): Add changelog script (#5677)

**Summary**

This diff simply adds a script to easily generate the changelog between the current tag and the previous one.

**Test plan**

Manually ran `yarn changelog`.

package.json

@@ -76,6 +76,7 @@
     "eslint-plugin-yarn-internal": "file:scripts/eslint-rules",
     "execa": "^0.10.0",
     "flow-bin": "^0.66.0",
+    "git-release-notes": "^3.0.0",
     "gulp": "^3.9.0",
     "gulp-babel": "^7.0.0",
     "gulp-if": "^2.0.1",
@@ -108,6 +109,7 @@
     "build-deb": "./scripts/build-deb.sh",
     "build-dist": "bash ./scripts/build-dist.sh",
     "build-win-installer": "scripts\\build-windows-installer.bat",
+    "changelog": "git-release-notes $(git describe --tags --abbrev=0 $(git describe --tags --abbrev=0)^)..$(git describe --tags --abbrev=0) scripts/changelog.md",
     "dupe-check": "yarn jsinspect ./src",
     "lint": "eslint . && flow check",
     "pkg-tests": "yarn --cwd packages/pkg-tests jest yarn.test.js",

scripts/changelog.md

@@ -0,0 +1,5 @@
+<% commits.forEach(function (commit) { %>
+* __<%= commit.title %>__
+
+    [<%= commit.authorName %>](mailto:<%= commit.authorEmail %>) - <%= commit.committerDate %>
+<% }) %>

yarn.lock

@@ -1842,6 +1842,10 @@ dashdash@^1.12.0:
   dependencies:
     assert-plus "^1.0.0"
 
+date-fns@^1.29.0:
+  version "1.29.0"
+  resolved "https://registry.yarnpkg.com/date-fns/-/date-fns-1.29.0.tgz#12e609cdcb935127311d04d33334e2960a2a54e6"
+
 date-now@^0.1.4:
   version "0.1.4"
   resolved "https://registry.yarnpkg.com/date-now/-/date-now-0.1.4.tgz#eaf439fd4d4848ad74e5cc7dbef200672b9e345b"
@@ -2056,6 +2060,10 @@ ecc-jsbn@~0.1.1:
   dependencies:
     jsbn "~0.1.0"
 
+ejs@^2.5.7:
+  version "2.5.8"
+  resolved "https://registry.yarnpkg.com/ejs/-/ejs-2.5.8.tgz#2ab6954619f225e6193b7ac5f7c39c48fefe4380"
+
 electron-to-chromium@^1.3.18:
   version "1.3.21"
   resolved "https://registry.yarnpkg.com/electron-to-chromium/-/electron-to-chromium-1.3.21.tgz#a967ebdcfe8ed0083fc244d1894022a8e8113ea2"
@@ -2790,6 +2798,15 @@ getpass@^0.1.1:
   dependencies:
     assert-plus "^1.0.0"
 
+git-release-notes@^3.0.0:
+  version "3.0.0"
+  resolved "https://registry.yarnpkg.com/git-release-notes/-/git-release-notes-3.0.0.tgz#3d8b1afcd2ebe0dd3f9449dc2a7106be4b7de5d3"
+  dependencies:
+    date-fns "^1.29.0"
+    debug "^3.1.0"
+    ejs "^2.5.7"
+    optimist "^0.6.1"
+
 glob-base@^0.3.0:
   version "0.3.0"
   resolved "https://registry.yarnpkg.com/glob-base/-/glob-base-0.3.0.tgz#dbb164f6221b1c0b1ccf82aea328b497df0ea3c4"
@@ -6385,7 +6402,7 @@ v8flags@^2.0.2:
   dependencies:
     user-home "^1.1.1"
 
-validate-npm-package-license@^3.0.3:
+validate-npm-package-license@^3.0.1, validate-npm-package-license@^3.0.3:
   version "3.0.3"
   resolved "https://registry.yarnpkg.com/validate-npm-package-license/-/validate-npm-package-license-3.0.3.tgz#81643bcbef1bdfecd4623793dc4648948ba98338"
   dependencies: