Currently using lifecycle in cell is not possible as that would introduce a cyclic dependency.
This moves the type definition of HookContext to a separate package, as
well as adds separate Lifecycle/HookInterface definitions that can be
imported by pkg/hive/cell.

Finally, pkg/hive now injects a wrapped hive.Lifecycle that converts pkg/hive/cell/lifecycle hooks.
Thus allowing pkg/cell to depend on lifecycle hooks.

This is done to avoid having to refactor the lifecycle types in pkg/hive
which would result in having to fix imports across the codebase.

Signed-off-by: Tom Hadlaw <tom.hadlaw@isovalent.com>

Structured health reporter initializes a context.Context object with a
module scoped cell.HealthReporter.

This can be then used to propegate a structured health reporter tree,
where leaves represent active health reporters and intermediary nodes
provide a common scope for all sub reporters.

In subsequent commits, this will be used to provide modular health
status reporting for more complex modules such as endpoint manager where
many "sub-components" must also be healthy in order for the module to
report as healthy.

Currently, this is an opt-in layer built on top of the existing
cell.HealthReporter interface, by layering functionality on the existing
health reporter provided by the cell.Module.

Currently the context is initialized with the structured tree reporter at the module level.
To avoid the risk of deadlocks, the entire reporter tree uses one lock
which is initialized when calling WithStructuredReporter. This is shared
among all subreporters.

 Example:

 1. Init root scope (note: this is provided to modules automatically).
 root := rootScope(ctx, hr)

	root

 2. Create endpoint-manager subscope, and reporter under that scope (with ok!)
 endpointManagerScope := GetSubScope(ctx, root, "endpoint-manager")
 GetHealthReporter(endpointManagerScope, "endpoint-000").OK("it works!")

	 root(OK)
		└── scope(endpoint-manager, OK)
			└── reporter(endpoint-000, OK)

 3. Create another reporter under that scope with degraded
 GetHealthReporter(endpointManagerScope, "endpoint-000").Degraded("oh no!")

	 root(Degraded)
		└── scope(endpoint-manager, Degraded)
			└── reporter(endpoint-000, OK)
			└── reporter(endpoint-000, Degraded)

 4. Close the endpoint-manager scope
 endpointManagerScope.Stopped("no more status to report!")

	root(OK) // status has been reported, but we no longer have any degraded status
		 // default to ok status.

Signed-off-by: Tom Hadlaw <tom.hadlaw@isovalent.com>