Move the A2A sample projects (A2AAgent_AsFunctionTools and
A2AAgent_PollingForTaskCompletion) from samples/04-hosting/A2A/ to
samples/02-agents/A2A/ to better align with the sample directory
structure. Update solution file and samples README accordingly.
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
SergeyMenshykh