Document FailOver messages for all the scenarios

Here's 4 types of messages that we display based on 4 combinations of up/down and mostly-up-to-date/not-up-to-date. "unknown" will mean not-up-to-date:

<div class="failover_warning pat_20 warning_up_backfill">
<h2>Fail Over Options</h2>
<label><input type="radio" name="failOver" value="startGracefulFailover"> <span>Graceful Fail Over (default).</span></label>
<label><input type="radio" name="failOver" value="failOver"> <span>Hard Fail Over - If you use hard failover option on a functioning node it may result in data loss. This is because failover will immediately remove the node from the cluster and any data that has not yet been replicated to other nodes may be permanently lost if it had not been persisted to disk.</span></label>
<div class="warning js_warning">
<strong>Attention</strong> – A significant amount of data stored on this node
does not yet have replica (backup) copies! Failing over the node now will
irrecoverably lose that data when the incomplete replica is
activated and this node is removed from the cluster. It is
recommended to select "Remove Server" and rebalance to
safely remove the node without any data loss.
<label><input type="checkbox" name="confirmation"> Please confirm Failover.</label>
</div>
</div>
<div class="failover_warning pat_20 warning_up_no_backfill">
<h2>Fail Over Options</h2>
<label><input type="radio" name="failOver" value="startGracefulFailover"> <span>Graceful Fail Over (default).</span></label>
<label><input type="radio" name="failOver" value="failOver"> <span>Hard Fail Over - If you use hard failover option on a functioning node it may result in data loss. This is because failover will immediately remove the node from the cluster and any data that has not yet been replicated to other nodes may be permanently lost if it had not been persisted to disk.</span></label>
<div class="warning js_warning">
<strong>Warning</strong> – Failing over the node will remove it from the cluster and activate a replica.
Operations currently in flight and not yet replicated, will be lost. Rebalancing will be required
to add the node back into the cluster. Consider using "Remove from Cluster" and rebalancing instead of Failover,
to avoid any loss of data. Please confirm Failover.
</div>
</div>
<div class="failover_warning pat_20 warning_down_backfill">
<input type="radio" name="failOver" value="failOver" style="display:none">
<div class="warning">
<strong>Attention</strong> – There are not replica (backup) copies of all data
on this node! Failing over the node now will irrecoverably
lose that data when the incomplete replica is activated and
this node is removed from the cluster. If the node might
come back online, it is recommended to wait.
Check this box if you want to failover the node, despite the resulting data loss
<label><input type="checkbox" name="confirmation"> Please confirm Failover.</label>
</div>
</div>
<div class="failover_warning pat_20 warning_down_no_backfill">
<input type="radio" name="failOver" value="failOver" style="display:none">
<div class="warning">
<strong>Warning</strong> – Failing over the node will remove it from the cluster and activate a replica.
Operations not replicated before the node became unresponsive, will be lost.
Rebalancing will be required to add the node back into the cluster. Please confirm Failover.
</div>
</div>
</div>