Sitespeed.io: [meta] Fix hash URLs

[soulgalore]

Let us collect the problems we have with hash URLs here:

1. By default, we strip everything after a hash in a URL when we create the file path. That works perfectly for the web by default but not with some of the frameworks.

If we have two URLs like this:
https://preview.pro.ant.design/#/dashboard/monitor
https://preview.pro.ant.design/#/dashboard/analysis

They will be the same URL on disk. What about adding a configuration parameter so you can choose to include the hash. That also needs to be done for the generic page generator for Graphite etc.

1. Accessing multiple URL with prescript with Chrome generates a Page.navigatedWithinDocument event (which is kind of cool since we then can measure a pre warmed SPA) but we don't handle that the right way when we add things to the HAR). #2087

[soulgalore]

For step 1:
Make sure we can configure to use the hash in https://github.com/sitespeedio/sitespeed.io/blob/master/lib/core/resultsStorage/pathToFolder.js#L7-L28 and in https://github.com/sitespeedio/sitespeed.io/blob/master/lib/support/flattenMessage.js#L15 - I think that will do it? But want your input @tobli before I do anything.

[soulgalore]

This was fixed in 8.0.