Add easy web based usage

[curtcox]

A lower barrier to entry would enhance the adoption and usefulness of the project. Consider the following scenarios that a repo owner might want:

• Adding a link to the repo that users could follow to an instance pre-configured for working on the repo.
• Adding a link to an issue that users could follow to an instance configured to work the issue.

These links could be added manually or by bots.

There are lots of potential options for where instances might run -- Replit, Colab, Github, ... The important thing is that more people will have the time and ability to use SWE-agent for working issues if doing so is as simple as possible. That is true even if they need to have a paid account somewhere to use the link.