feat: Create Hacker mode theme #1988 (#2091)

* feat: Create Hacker mode theme #1988

I created a theme with a black bacground, black block fill for all blocks, a white shadow for all blocks (still working on putting in an actual outline),
dark toolbox, dark flyout, and monospace text. I am still working on putting in green text for all block text. Need to fix CSS issue first.

* fix: fixing formatting errors in the hackermode theme
Made theme private, updated descriptions, and updated formatting errors in readme, pagkage.json and index.

* feat: Create Hacker mode theme
Deleted out To-do comments and marked the package private in the package.json file.

* fix: resolve build errors in theme-hackermode
Deleted line 1 in index that privated the file so that build can run successfully.

* fix: formatting issues in hackermode theme.
Ran npm ci and npm run format to fix formatting issues.

* chore: format

---------

Co-authored-by: Beka Westberg <bwestberg@google.com>

plugins/theme-hackermode/.npmignore

@@ -0,0 +1,24 @@
+# See https://help.github.com/articles/ignoring-files/ for more about ignoring files.
+
+# dependencies
+/node_modules
+/.pnp
+.pnp.js
+
+# testing
+/coverage
+
+# production
+/build
+/dist
+
+# misc
+.DS_Store
+.env.local
+.env.development.local
+.env.test.local
+.env.production.local
+
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*

plugins/theme-hackermode/README.md

@@ -0,0 +1,32 @@
+# @blockly/theme-hackermode [![Built on Blockly](https://tinyurl.com/built-on-blockly)](https://github.com/google/blockly)
+
+A [Blockly](https://www.npmjs.com/package/blockly) theme that is designed to look like a movie hacker screen. It has a black background, black blocks and lime green text.
+
+## Installation
+
+### Yarn
+
+```
+yarn add @blockly/theme-hackermode
+```
+
+### npm
+
+```
+npm install @blockly/theme-hackermode --save
+```
+
+## Usage
+
+```js
+import * as Blockly from 'blockly';
+import Theme from '@blockly/theme-hackermode';
+
+Blockly.inject('blocklyDiv', {
+  theme: Theme,
+});
+```
+
+## License
+
+Apache 2.0