feat: namespaced pages

[lwrogersjr]

Would like the ability to use simple namespaces to disambiguate common names for pages that have very different meanings.

In Roam, if you have two pages that have the same name but different meanings, you can put a / in the name. The prefix will not be rendered.

• e.g., [[Datastructures/Tree]]s are much more commonly used for organizing notes than [[Datastructures/Graphs]], but they are far less powerful.
• e.g., I love climbing [[Plants/Tree]]s.
• You can toggle how much of the prefix you are showing at any time by hitting control-c control-l

[BradKML]

Some extra ideas: being able to tuck certain pages under others with one click. e.g. one wants to tuck page "B" under "A" and it becomes "A/B" with "alias:: B" Reference for this issue: https://github.com/athensresearch/athens/issues/828