context_server: Fix casing of `mimeType` in tool responses (#30703)

Closes #30243

Release Notes:

- Fixed wrong casing for the `mimeType` field when parsing MCP server
image responses.
49f3ec7f35Jonathan LEI committed on 5/26/2025, 8:29:45 AM· committed by GitHubparent7488405
1 file changedLine totals unavailable