add clippy support to rust and show detailed diagnostics on hover

lua/lsp/rust.lua

@@ -0,0 +1,19 @@
+local M = {
+  ['rust-analyzer'] = {
+     assist = {
+       importGranularity = "module",
+       importPrefix = "by_self",
+     },
+     cargo = {
+       loadOutDirsFromCheck = true
+     },
+     procMacro = {
+       enable = true
+     },
+     checkOnSave = {
+       command = "clippy"
+     },
+  }
+}
+
+return M