Frontend: Add hostdetails BackLink fallback path (#9262)

# Addresses #9141 

# Fixes
- 'Back to all hosts' link on Host Details page was navigating
incorrectly when the user had previously navigated directly with the
browser URL. This prevents this bug by adding a fallback path for that
BackLink to the default Manage Hosts path.

https://www.loom.com/share/579501365f514ac488f86eacadb2fd07

# Checklist for submitter

If some of the following don't apply, delete the relevant line.

- [x] Changes file added for user-visible changes in `changes/`
- [x] Manual QA for all new/changed functionality

Co-authored-by: Jacob Shandling <jacob@fleetdm.com>

changes/9141-host-details-backlink-bug

@@ -0,0 +1,3 @@
+- Made the 'Back to all hosts' link on the host details page fall back to the default path to the
+  manage hosts page. This addresses a bug in this functionality when the user navigates directly
+  with the URL

frontend/pages/hosts/details/HostDetailsPage/HostDetailsPage.tsx

@@ -627,7 +627,10 @@ const HostDetailsPage = ({
     <MainContent className={baseClass}>
       <div className={`${baseClass}__wrapper`}>
         <div className={`${baseClass}__header-links`}>
-          <BackLink text="Back to all hosts" path={filteredHostsPath} />
+          <BackLink
+            text="Back to all hosts"
+            path={filteredHostsPath || PATHS.MANAGE_HOSTS}
+          />
         </div>
         <HostSummaryCard
           statusClassName={statusClassName}