Adds option to install UCX in offline mode (#3959)

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Resolves #3418 

### Functionality

- [ ] added relevant user documentation

Author: HariGS-DB

docs/ucx/docs/installation/index.mdx

@@ -200,6 +200,15 @@ PIP_INDEX_URL="https://url-to-company-hosted-pypi.internal" databricks labs inst
 
 During installation reply *yes* to the question "Does the given workspace block Internet access"?
 
+In case if host has no access to github, then ucx installation will not be able to download the files locally and fail.
+In order to address that, follow the steps below
+ - install ucx on a host which has access to github using the instruction above
+ - zip the installation from ~/.databricks/labs/ucx
+ - copy the zip file to the target host and unzip
+Now the installation can be done in offline mode (ensure databricks cli is upgrade to version v0.244.0 or higher)
+```commandline
+PIP_INDEX_URL="https://url-to-company-hosted-pypi.internal" databricks labs install ucx --offline=true
+```
 
 
 ## Upgrading UCX for newer versions
@@ -237,4 +246,4 @@ Databricks CLI will confirm a few options:
 - Whether you want to remove all ucx artefacts from the workspace as well. Defaults to no.
 - Whether you want to delete the inventory database in `hive_metastore`. Defaults to no.
 
-![macos_uninstall_ucx](/img/macos_4_databrickslabsmac_uninstallucx.gif)
+![macos_uninstall_ucx](/img/macos_4_databrickslabsmac_uninstallucx.gif)