feat: Add 'Export Query Result' button which downloads csv file of query result set

[dylanrigal1999]

I've used this tool a bit and I am finding it useful. As pointed out here #2, it would be nice if you could download the result of a query, so that is what this pull request is for.

I am new to node.js, so maybe some of this could be done better, not sure. It seems to work well though.

Would be cool if this got merged.

[dumbmatter]

Sorry for the late reply. Thanks for the PR! It looks good, but I am not really maintaining this project lately so idk when I will actually merge and update it. But feel free to put your own version online somewhere if you'd like!