feat: fix re-entrancy in strategies

[nbaztec]

What 💻

• Fixes re-entrancy issue by separating the context from the strategy.
• Strategy is split into Runner and Context, which can be partially borrowed.
• Runner implements all methods with immutable &self and takes the &mut Context to mutate.
• Context is implemented via Any and is downcastable and specific to each implementation.
• In places where self parameter is passed into the strategy objects:
  • &mut Context may be omitted as it's available via self.strategy.context.
  • The stateless self.strategy.runner can be cloned and dissociated from self: self.strategy.runner.clone().foo(self).

Why ✋

• Required for re-entrancy

Evidence 📷

Tests pass