Modify Pre/Post-Reconciliation Extensions to provide a Resolver

[theunrepentantgeek]

What this PR does / why we need it:

The two extension points PreReconciliationChecker and PostReconciliationChecker provide numerous parameters to enable extension implementations to easily achieve their goals.

We passed through a kubeclient.Client by design, but have found this to be difficult to consume because our resources often have a genruntime.ResourceReference but kubeclient.Client requires a GVK.

Replacing kubeclient.Client with resolver.Resolver bridges this gap, allowing extension implementers to simply call ResolveReference() and not fuss with GVK (etc).

Closes #3092

How does this PR make you feel:

[codecov-commenter]

Codecov Report

Merging #3105 (56ff069) into main (d882264) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #3105      +/-   ##
==========================================
+ Coverage   54.23%   54.25%   +0.01%     
==========================================
  Files        1418     1418              
  Lines      609010   609010              
==========================================
+ Hits       330312   330432     +120     
+ Misses     224596   224472     -124     
- Partials    54102    54106       +4     

Impacted Files	Coverage Δ
...rvice/customizations/managed_cluster_extensions.go	65.15% <ø> (ø)
...izations/managed_clusters_agent_pool_extensions.go	43.47% <ø> (ø)
...resql/customizations/flexible_server_extensions.go	64.28% <ø> (ø)
...omizations/flexible_servers_database_extensions.go	22.22% <ø> (ø)
...tions/flexible_servers_firewall_rule_extensions.go	44.44% <ø> (ø)
...ork/customizations/private_endpoints_extensions.go	29.41% <ø> (ø)
...ilers/arm/azure_generic_arm_reconciler_instance.go	68.88% <100.00%> (ø)
...enruntime/extensions/postreconciliation_checker.go	48.83% <100.00%> (ø)
...genruntime/extensions/prereconciliation_checker.go	50.00% <100.00%> (ø)

... and 27 files with indirect coverage changes

[matthchr]

minor: import ordering

[matthchr]

And in other files

[theunrepentantgeek]

Fixed.