rust: Move ignores to top .gitignore

Apply the rules to ignore some cargo generated or used files to the
whole tree, not just the samples.

Signed-off-by: David Brown <[email protected]>

Author: d3zd3z

.gitignore

@@ -59,6 +59,14 @@ venv
 .clangd
 new.info
 
+# Cargo drops lock files in projects to capture resolved dependencies.
+# We don't want to record these.
+Cargo.lock
+
+# Cargo encourages a .cargo/config.toml file to symlink to a generated
+# file.  Don't save these.
+.cargo/
+
 # CI output
 compliance.xml
 _error.types