replace "dep" with "go mod"

A simple "go mod init && go mod tidy && go mod vendor" was enough and
mostly seems to have picked the same revisions of the dependencies as
before. Notable exceptions are klog and gogo/protobuf.

vendor/k8s.io/client-go/tools/auth/OWNERS

@@ -0,0 +1,9 @@
+# See the OWNERS docs at https://go.k8s.io/owners
+
+approvers:
+- sig-auth-authenticators-approvers
+reviewers:
+- sig-auth-authenticators-reviewers
+labels:
+- sig/auth
+

vendor/k8s.io/client-go/tools/cache/OWNERS

@@ -0,0 +1,51 @@
+# See the OWNERS docs at https://go.k8s.io/owners
+
+approvers:
+- thockin
+- lavalamp
+- smarterclayton
+- wojtek-t
+- deads2k
+- caesarxuchao
+- liggitt
+- ncdc
+reviewers:
+- thockin
+- lavalamp
+- smarterclayton
+- wojtek-t
+- deads2k
+- brendandburns
+- derekwaynecarr
+- caesarxuchao
+- mikedanese
+- liggitt
+- nikhiljindal
+- erictune
+- davidopp
+- pmorie
+- janetkuo
+- justinsb
+- eparis
+- soltysh
+- jsafrane
+- dims
+- madhusudancs
+- hongchaodeng
+- krousey
+- markturansky
+- fgrzadkowski
+- xiang90
+- mml
+- ingvagabund
+- resouer
+- jessfraz
+- david-mcmahon
+- mfojtik
+- '249043822'
+- lixiaobing10051267
+- ddysher
+- mqliang
+- feihujiang
+- sdminonne
+- ncdc

vendor/k8s.io/client-go/tools/leaderelection/OWNERS

@@ -0,0 +1,15 @@
+# See the OWNERS docs at https://go.k8s.io/owners
+
+approvers:
+- mikedanese
+- timothysc
+reviewers:
+- wojtek-t
+- deads2k
+- mikedanese
+- gmarek
+- eparis
+- timothysc
+- ingvagabund
+- resouer
+- goltermann

vendor/k8s.io/client-go/tools/metrics/OWNERS

@@ -0,0 +1,9 @@
+# See the OWNERS docs at https://go.k8s.io/owners
+
+reviewers:
+- wojtek-t
+- eparis
+- krousey
+- jayunit100
+- fgrzadkowski
+- tmrts

vendor/k8s.io/client-go/tools/record/OWNERS

@@ -0,0 +1,29 @@
+# See the OWNERS docs at https://go.k8s.io/owners
+
+reviewers:
+- lavalamp
+- smarterclayton
+- wojtek-t
+- deads2k
+- derekwaynecarr
+- caesarxuchao
+- vishh
+- mikedanese
+- liggitt
+- nikhiljindal
+- erictune
+- pmorie
+- dchen1107
+- saad-ali
+- luxas
+- yifan-gu
+- eparis
+- mwielgus
+- timothysc
+- jsafrane
+- dims
+- krousey
+- a-robinson
+- aveshagarwal
+- resouer
+- cjcullen