Add ChromeOS enterprise param for showing the Troubleshooting tools

This CL adds a new flag which will be used to indicate whether to show
the troubleshooting tools in the UI. In previous milestones, the
`allow_troubleshooting_tools` flag was overloaded to mean both 'show'
and 'enabled' however this meant that the client could not provide and
help text or links if the feature was disabled by policy.

Since this feature changes the semantics of `allow_troubleshooting_tools`,
the CRD backend will be updated to populate the `show_...` flag based on
whether the `allow_...` flag is set.

Change-Id: Ic582bbb96674a9924aed55401428cd437a597e6d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4617584


Commit-Queue: Irina Fedorova <irfedorova@google.com>
Auto-Submit: Joe Downing <joedow@chromium.org>
Reviewed-by: Jamie Walch <jamiewalch@chromium.org>
Reviewed-by: Irina Fedorova <irfedorova@google.com>
Cr-Commit-Position: refs/heads/main@{#1159582}