[Feature/Plugin API] Add clipboard wrapper methods to context app

[jasonblalock]

• Adds clipboard object with .readText and .writeText methods using
  underlying electorn clipboard methods

Closes INS-919

[develohpanda]

Nice! Verified with a small plugin I made to QA, which exports a workspace directly into your clipboard! Ever since you talked about the clipboard API being available to plugins, I've had so many quality-of-life ideas which can be built out as plugins 🙌🏽

For anybody else looking at this, there is further discussion about this in the Insomnia Slack.

module.exports.workspaceActions = [
  {
    action: async (context, {workspace}) => {
      const exportContents = await context.data.export.insomnia(workspace);

      // This is new!!
      context.app.clipboard.writeText(exportContents);

      await context.app.alert('Exported to clipboard', `The workspace ${workspace.name} has been exported to your clipboard.`);
    },
    label: 'Export to clipboard',
  },
]

[wdawson]

Looks great to me! ⛵ Thanks for the work on this!

[dimitropoulos]

lgtm - thanks! This oughta be useful!