Shadowed Predeclared Indentifier analyzer (#7215)

* wip

* working for some ast nodes

* works for all but assignment

* works for all but mixed assignments

* change test name

* plug in the analyzer

* remove `copy` from predeclared list

* rename few shadowing names

* rename `len` to `length`

* add one more test case

* rename `panic` to `panicResult`

* replace `panic` with `panicResult` in error message

* remove test case not covered by the tool

* add `byte` to predeclared list

* additional test cases

* rename `copy` to `copyHandler`

* exclude functions with receivers

* revert to good names

Co-authored-by: prylabs-bulldozer[bot] <58059840+prylabs-bulldozer[bot]@users.noreply.github.com>

BUILD.bazel

@@ -109,6 +109,7 @@ nogo(
         "//tools/analyzers/errcheck:go_tool_library",
         "//tools/analyzers/featureconfig:go_tool_library",
         "//tools/analyzers/comparesame:go_tool_library",
+        "//tools/analyzers/shadowpredecl:go_tool_library",
     ] + select({
         # nogo checks that fail with coverage enabled.
         ":coverage_enabled": [],