Add DeregisterAll and automatic indicator deregistration on security removal

[jhonabreul]

Description

Universe churn leaks helper-created indicators and consolidators: when a security leaves the universe, consolidators created by the indicator helpers are never disposed and keep being re-scanned forever. Algorithms with per-symbol state and add/remove churn accumulate them until an OutOfMemoryException hours into a run.

The change:

• QCAlgorithm.DeregisterAll(Symbol) — one-line cleanup of everything the helpers created for a symbol. RegisterConsolidator (the choke point all helpers funnel through) now tracks indicators/consolidators per symbol; DeregisterAll disposes them via the existing paths.
• Multi-symbol indicators (e.g. B(target, reference)) are fully deregistered through any of their symbols.
• Consolidators added directly via SubscriptionManager.AddConsolidator are intentionally not tracked, so they survive universe removals.
• Settings.AutomaticIndicatorDeregistration (default false) — opt-in automatic DeregisterAll when a security is removed from the algorithm.
• Fixes a leak in SubscriptionManager.RemoveConsolidator: the scan wrapper was only disposed while the symbol still had subscription configs, so post-universe-removal cleanup left it in the scan queue forever. It is now disposed unconditionally.

Also audited: a user-state slot on Security already exists (security["my_state"] = obj via DynamicObject) — documentation gap, no engine work. Split-safe re-warm of selection indicators is deferred: there is no engine-side seam to user filter functions, and feeding adjusted prices avoids the problem.

Related Issue

N/A

Motivation and Context

Per-symbol cleanup on universe removal takes a hand-rolled loop today, and getting it wrong is invisible until an OOM. A one-line (or automatic) cleanup makes the correct pattern the easy one.

Requires Documentation Change

Yes: DeregisterAll and Settings.AutomaticIndicatorDeregistration, next to DeregisterIndicator and the universe cleanup examples.

How Has This Been Tested?

• New AlgorithmDeregisterAllTests (7 tests): target-symbol-only disposal, multi-symbol indicators, no-op after manual deregistration, raw AddConsolidator consolidators kept, automatic deregistration on removal iff the setting is on.
• New SubscriptionManagerTests case reproducing the wrapper leak: red before the fix, green after.
• New DeregisterAllRegressionAlgorithm (C# + Python) and AutomaticIndicatorDeregistrationRegressionAlgorithm (C#): add/remove churn, cleanup asserted, fresh indicators work after re-adding.
• Related suites green: 472 passed, 0 failed; full Tests.Algorithm namespace with CI filters.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• Refactor (non-breaking change which improves implementation)
• Performance (non-breaking change which improves performance. Please add associated performance test and results)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Non-functional change (xml comments/documentation/etc)

Checklist:

• My code follows the code style of this project.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.
• My branch follows the naming convention bug-<issue#>-<description> or feature-<issue#>-<description>