bigquery: rename uploader*.go to inserter*.go

Change-Id: I7e8c730d827f206975df7dfced6f60fd47e42aae
Reviewed-on: https://code-review.googlesource.com/c/35210
Reviewed-by: Eno Compton <enocom@google.com>
Reviewed-by: kokoro <noreply+kokoro@google.com>
diff --git a/bigquery/uploader.go b/bigquery/inserter.go
similarity index 100%
rename from bigquery/uploader.go
rename to bigquery/inserter.go
diff --git a/bigquery/uploader_test.go b/bigquery/inserter_test.go
similarity index 100%
rename from bigquery/uploader_test.go
rename to bigquery/inserter_test.go