Calling `_convert_mcp_content_to_lc_block` with a `ResourceLink` conflicts with `langchain-aws` `_messages_to_bedrock` (and possibly others)

`_convert_mcp_content_to_lc_block` maps an MCP `ResourceLink` to a *URL-sourced* file or image content block ([`tools.py`](https://github.com/langchain-ai/langchain-mcp-adapters/blob/main/langchain_mcp_adapters/tools.py#L204-L208)): ```python if isinstance(content, ResourceLink): mime_type = content.mimeType or None if mime_type and mime_type.startswith("image/"): return create_image_block(url=str(content.uri), mime_type=mime_type) return create_file_block(url=str(content.uri), mime_type=mime_type) ``` This causes two problems: **1. URL-sourced file blocks are not universally supported.** Bedrock Converse only supports `document.source.bytes` — it has no URL document source — so `langchain-aws` raises `ValueError: File data only supported through in-line base64 format.` The result: **a single `ResourceLink` anywhere in a tool result terminates the agent run.** It is not recoverable by the caller either — `handle_tool_errors` does not apply (this isn't an `isError=True` result), and the failure happens later still, at model-invoke time, once the `ToolMessage` is already in the message list. **2. MCP resource URIs are often not dereferenceable URLs.** A `ResourceLink` is a pointer to be read back via `resources/read` on the MCP session — not necessarily a web-fetchable address. Servers commonly use custom schemes; the reference server returns `demo://resource/dynamic/blob/1`. Even a provider that *does* accept URL sources cannot fetch that. Mapping a resource URI onto a URL source conflates two different things. ### Reproduction No MCP server and no AWS credentials needed — this feeds a `ResourceLink` straight through the adapter's own conversion function and into the Bedrock message formatter: ```python from langchain_core.messages import ToolMessage from mcp.types import ResourceLink from langchain_mcp_adapters.tools import _convert_mcp_content_to_lc_block from langchain_aws.chat_models.bedrock_converse import _messages_to_bedrock link = Resou…