ethdb, rpc: support building on js/wasm (#17709)

The changes allow building WebAssembly applications which use ethclient.Client.

ethdb/database_test.go

@@ -14,6 +14,8 @@
 // You should have received a copy of the GNU Lesser General Public License
 // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
 
+// +build !js
+
 package ethdb_test
 
 import (