CHASM: deserialize ChasmNode into tree node value (temporalio#7538)

## What changed?
<!-- Describe what has changed in this PR -->
CHASM: deserialize `ChasmNode` into tree node `value`. This is only
first version with few TODOs to be resolved soon.

## Why?
<!-- Tell your future self why have you made these changes -->
CHASM worksream.

## How did you test it?
<!-- How have you verified this change? Tested locally? Added a unit
test? Checked in staging env? -->
Added unit tests.

## Potential risks
<!-- Assuming the worst case, what can be broken when deploying this
change to production? -->
No risks.

## Documentation
<!-- Have you made sure this change doesn't falsify anything currently
stated in `docs/`? If significant
new behavior is added, have you described that in `docs/`? -->
No.

## Is hotfix candidate?
<!-- Is this PR a hotfix candidate or does it require a notification to
be sent to the broader community? (Yes/No) -->
No.

Author: alexshtin

chasm/component.go

@@ -26,7 +26,10 @@
 
 package chasm
 
-import "context"
+import (
+	"context"
+	"reflect"
+)
 
 type Component interface {
 	LifecycleState() LifecycleState
@@ -51,6 +54,8 @@ func (UnimplementedComponent) LifecycleState() LifecycleState {
 
 func (UnimplementedComponent) mustEmbedUnimplementedComponent() {}
 
+var UnimplementedComponentT = reflect.TypeFor[UnimplementedComponent]()
+
 // Shall it be named ComponentLifecycleState?
 type LifecycleState int