Rename repo to open62541-rs

[uklotzde]

Context:

• Custom Nodesets and DataType Handling #172
• https://github.com/basyskom-dege/open62541_rust

I just noticed that renaming might be necessary when forking this repo. Keeping a fork of the original C library is not an uncommon situation for contributors.

We should have named the repo open62541-rs to prevent such naming conflicts. By forking https://github.com/open62541/open62541 ourselves we might have noticed this earlier. We could still rename it.

The name of the crate is fine.

[sgoll]

When forking on GitHub, you can pick a custom repository name for your clone of any repository. I am not sure that this is such a relevant problem. I have run across this myself and saw no issue in picking open62541-rs for my copy of the code.