fix: base option not generating correct multi sidebar (#231)

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fix #231

Fixes the issue where when base option is set, multi sidebar fails to retrieve correct sidebar config.

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Not directly related to this fix or issue but we get Hydration completed but contains mismatches. when using base option. Seems like active link check for nav items is causing the issue. Will look into a bit deeper and try if I can include the fix in this PR.

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I think i've fixed it. But I'm maybe not 100% happy with the solution. Maybe we should add another param on route to retrieve path without base, and use that to do any active link checks. That way, the active link check should always work regardless of the base option.

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And I did.