fix(mermaid): switch to crates.io and patch dagre_rust panic

Switch mermaid-rs-renderer from git dependency to crates.io 0.1.

Vendor and patch dagre_rust 0.0.5 to fix upstream panic in
remove_edge_label_proxies() where unwrap() is called on None
when processing edge label proxies without edge references.

This enables sequence diagrams and state diagrams that previously
crashed the build.

patches/dagre_rust/README.md

@@ -0,0 +1,9 @@
+# dagre-rust
+
+dagre-rust is a Rust implementation of [graphlib](https://github.com/dagrejs/dagre) that helps drawing DAG.
+
+# License
+
+Dagre is licensed under the terms of the Apache-2.0 License. See the
+[LICENSE](LICENSE) file
+for details.