Scope macro (#3136)

* add scope proc macro

* Update scope macro code to work with current HttpServiceFactory

* started some test code

* add some unit tests

* code formatting cleanup

* add another test for combining and calling 2 scopes

* format code with formatter

* Update actix-web-codegen/src/lib.rs with comment documentation fix

Co-authored-by: oliver <151407407+kwfn@users.noreply.github.com>

* work in progress. revised procedural macro to change othe macro call

* add tests again. refactor nested code.

* clean up code. fix bugs with route and method attributes with parameters

* clean up for rust fmt

* clean up for rust fmt

* fix out of date comment for scope macro

* sync to master branch by adding test_wrap

* needed to format code

* test: split out scope tests

* test: add negative tests

* chore: move imports back inside (?)

* docs: tweak scope docs

* fix: prevent trailing slashes in scope prefixes

* chore: address clippy lints

---------

Co-authored-by: oliver <151407407+kwfn@users.noreply.github.com>
Co-authored-by: Rob Ede <robjtede@icloud.com>

actix-web-codegen/tests/trybuild/scope-on-handler.stderr

@@ -0,0 +1,5 @@
+error: #[scope] macro must be attached to a module
+ --> tests/trybuild/scope-on-handler.rs:4:1
+  |
+4 | async fn index() -> &'static str {
+  | ^^^^^