feat(tools): Add conversation history to ToolContext

[tzolov]

• Add TOOL_CONVERSATION_KEY constant to store conversation history
• Extend ToolContext with getToolConversationHistory method
• Include conversation history in tool context during function execution
• Add test coverage for tool conversation history verification

Resolves #1202

Decisions to make:

• [ ] Should we have a dedicated FunctionCallingOption property to control the addition of the current tool conversation history to the TooContext. Or assume that any ToolContext will provide this information?
• [ ] Should we have a dedicated ToolContext#getToolConversationHistory or use the raw map with predefined key TOOL_CONVERSATION_KEY.

[ilayaperumalg]

LGTM, merging.

[ilayaperumalg]

Squashed, rebased, updated the javadoc, verified the changes and merged as 0eacc919