yew-router: Dynamic basename.

[finnbear]

Description

1. Currently, if basename changes, the URL isn't updated and the old basename is persisted until the next navigation. With this PR, basename changes take effect immediately.
2. Currently, if basename is initially Some, the URL may lack the basename until the next nagvigation. With this PR, the basename is immediately added to the URL.

Motivation

In my application, base path is used for something resembling a workspace while route is used for something resembling a page id with parameters. The base path may not exist (the default 'workspace') or may change (when moving between 'workspaces').

Checklist

• I have reviewed my own code
• I have tested my changes in my app
• I have added tests modified existing test to test all new functionality

[ranile]

Thanks for making the change. I have just one more concern here. Other than that, it looks good.

[ranile]

Thanks a lot!