Add a directory searcher that uses ripgrep as the backend

package.json

@@ -162,6 +162,7 @@
     "tree-view": "https://www.atom.io/api/packages/tree-view/versions/0.228.0/tarball",
     "typescript-simple": "1.0.0",
     "update-package-dependencies": "https://www.atom.io/api/packages/update-package-dependencies/versions/0.13.1/tarball",
+    "vscode-ripgrep": "^1.2.5",
     "welcome": "https://www.atom.io/api/packages/welcome/versions/0.36.9/tarball",
     "whitespace": "https://www.atom.io/api/packages/whitespace/versions/0.37.7/tarball",
     "winreg": "^1.2.1",

script/lib/generate-startup-snapshot.js

@@ -69,6 +69,7 @@ module.exports = function (packagedAppPath) {
         requiredModuleRelativePath === path.join('..', 'node_modules', 'yauzl', 'index.js') ||
         requiredModuleRelativePath === path.join('..', 'node_modules', 'winreg', 'lib', 'registry.js') ||
         requiredModuleRelativePath === path.join('..', 'node_modules', '@atom', 'fuzzy-native', 'lib', 'main.js') ||
+        requiredModuleRelativePath === path.join('..', 'node_modules', 'vscode-ripgrep', 'lib', 'index.js') ||
         // The startup-time script is used by both the renderer and the main process and having it in the
         // snapshot causes issues.
         requiredModuleRelativePath === path.join('..', 'src', 'startup-time.js')

spec/fixtures/dir/c

@@ -0,0 +1,19 @@
+line 1
+line 2
+line 3
+line 4
+line 5
+result 1
+line 6
+line 7
+line 8
+line 9
+line 10
+result 2
+result 3
+line 11
+line 12
+result 4
+line 13
+line 14
+line 15

spec/fixtures/dir/file-with-newline-literal

@@ -0,0 +1,7 @@
+newline1
+newline2
+newline3
+first
+second\nthird
+newline4
+newline5

spec/fixtures/dir/file-with-unicode

@@ -0,0 +1 @@
+ДДДДДДДДДДДДДДДДДД line with unicode