Add prefix /db/ to database route and subroutes

[pavish]

Fixes #2402

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[seancolsen]

Looks good. Works well.

[seancolsen]

@pavish I think this change is worth calling out specifically in the release notes because it will break any hyperlinks that people might have outside Mathesar which refer to Mathesar tables etc. Not a huge problem at our early stage, but it's the kind of thing that we'll need to be increasingly careful about as more people rely on Mathesar.