feat: allow function for NavItem link

[its-miroma]

Description

Similar to editLink, this PR allows links of Nav Bar items to be defined as functions that take in PageData.

For example, this allows a nav bar item to show an older version of the currently open page:

nav: [{
  text: "Show Page in V1",
  link: ({ relativePath }) => relativePath.replace(/^[/]/, "/v1/"),
}]

Linked Issues

none

Additional Context

• The translations under docs are generated by AI. I unfortunately do not speak any of those languages.

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Tip

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[brc-dd]

Thanks. LGTM.

The translations under docs are generated by AI. I unfortunately do not speak any of those languages.

Yeah that's fine. You didn't need to write those too, someone from the community would've picked up.

[its-miroma]

Should I drop them?

[brc-dd]

Nah, those seem to be fine. I'll merge.