Pull request: all: add stub binary for new api

Merge in DNS/adguard-home from new-api to master

Squashed commit of the following:

commit 83f4418c253b9abc5131d9e2acc2a4a96e4122c4
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Tue Apr 26 19:09:34 2022 +0300

    all: fix build

commit 1fbb53fdf779bde79fab72f9c8eb929e08bb044c
Merge: 73a55197 1c89394a
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Tue Apr 26 18:37:27 2022 +0300

    Merge branch 'master' into new-api

commit 73a5519723f662979bdeb5192bc15835e7f03512
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Tue Apr 26 18:36:50 2022 +0300

    v1: imp names, docs

commit d3fbc2f2082612b8ba438c8216c6c74421cc2df5
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Fri Apr 22 17:55:42 2022 +0300

    cmd: imp docs

commit c2a73aa364a848e8066d1132d4b53bbc3e22db2d
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Fri Apr 22 16:19:14 2022 +0300

    all: add stub binary for new api

Makefile

@@ -34,6 +34,8 @@ YARN_INSTALL_FLAGS = $(YARN_FLAGS) --network-timeout 120000 --silent\
 	--ignore-engines --ignore-optional --ignore-platform\
 	--ignore-scripts
 
+V1API = 0
+
 # Macros for the build-release target.  If FRONTEND_PREBUILT is 0, the
 # default, the macro $(BUILD_RELEASE_DEPS_$(FRONTEND_PREBUILT)) expands
 # into BUILD_RELEASE_DEPS_0, and so both frontend and backend
@@ -61,6 +63,7 @@ ENV = env\
 	PATH="$${PWD}/bin:$$( "$(GO.MACRO)" env GOPATH )/bin:$${PATH}"\
 	RACE='$(RACE)'\
 	SIGN='$(SIGN)'\
+	V1API='$(V1API)'\
 	VERBOSE='$(VERBOSE)'\
 	VERSION='$(VERSION)'\