Reorganize the Agent Flow Install topics into single task topics (#4232…

…) (#4272)

* First draft of the install config start reorg

* Update macOS and Windows topics

* Move topics to match Grafana docs arch

* Fix relrefs in docer topic

* Second pass at relrefs in docker topic

* More relref corrections

* Fix more relrefs

* Clean up metadata and add missing info

* Update Windows uninstall

* Fix markdown in note

* Clean up spacing between steps

* Add missing space between steps

* Fix alias redirects

* Expand navigation titles for clarity

* Small tweaks to the nav

* Shorten nav titles

* Update headings for consistency

* Update missed nav title

(cherry picked from commit b71f228)

docs/sources/flow/_index.md

@@ -67,7 +67,7 @@ prometheus.remote_write "default" {
 * Check out our [Reference][] documentation to find specific information you
   might be looking for.
 
-[Install]: {{< relref "./install/" >}}
+[Install]: {{< relref "./setup/install/" >}}
 [Concepts]: {{< relref "./concepts/" >}}
 [Getting started]: {{< relref "./getting-started/" >}}
 [Tutorials]: {{< relref "./tutorials/ ">}}