feat: add deployment to web stores

[ColdSauce]

Hey @ineo6, we created a Github action to make it easier to publish extensions to the various web stores.

Thought you might find it useful so I added a Github workflow that will run the build step for each browser (except Safari. We're building out support for that soon but don't have that working yet) and publish to the web stores on dispatch.

The only thing you would need to create is a SUBMIT_KEYS GitHub repository secret.

This secret is a JSON, with the schema defined here.

Here's a sample key:

{
  "$schema": "https://raw.githubusercontent.com/plasmo-corp/bpp/v1/keys.schema.json",
  "chrome": {
    "zip": "./extension/chrome.zip",
    "clientId": "123",
    "clientSecret": "456",
    "refreshToken": "789",
    "extId": "abcd"
  },
  "firefox": {
    "zip": "./extension/firefox.xpi",
    "apiKey": "123",
    "apiSecret": "abcd",
    "extId": "foobar"
  }
}

You can find instructions on how to get those keys in the schema, or if you use vscode, the schema should provide hint/intelisense when hovering over the json properties. If you need any help in setting up the keys, feel free to @ me.

Otherwise, if this doesn't seem necessary, feel free to close the PR!