feature: Add capability to hide the root url

[frodoagu]

This pull request introduces a new configuration option, HideRootPath, to the Index handler, allowing the application to conditionally hide the root path by returning a 404 response. The changes also ensure the Config field is properly initialized in relevant handlers.

This relates to #992

New feature: Conditional hiding of the root path

• server/handler/index.go: Added a Config field to the Index struct to access configuration options.
• server/handler/index.go: Updated the ServeHTTP method of the Index handler to check the HideRootPath configuration and return a 404 response if it is set to true.

Initialization updates

• server/server.go: Ensured the Config field is initialized in the Index handler during server setup.

[palantirtech]

Thanks for your interest in palantir/policy-bot, @frodoagu! Before we can accept your pull request, you need to sign our contributor license agreement - just visit https://cla.palantir.com/ and follow the instructions. Once you sign, I'll automatically update this pull request.

[asvoboda]

this is not the right location to add this change. You need to update the config in https://github.com/palantir/policy-bot/blob/develop/server/config.go

[frodoagu]

@asvoboda Just realized that I modified a go package, should I submit a PR to palantir/go-githubapp? seems that there is the place where the env variables are read from

[asvoboda]

No, your changes should be able to fit entirely within this repo. I'd recommend reading https://github.com/palantir/policy-bot?tab=readme-ov-file#development to get policy bot to run locally.