[#488] reputation: Change Writer interface

Includes:
- Delete first `ctx` argument in `Write` method.
- Move intermediate Initial trust struct and method
to `calculator` file.
- Change Alpha to 0.1.

Signed-off-by: Pavel Karpy <carpawell@nspcc.ru>

cmd/neofs-node/reputation/common/util.go

@@ -3,7 +3,6 @@ package common
 import (
 	"context"
 	"fmt"
-	"github.com/nspcc-dev/neofs-node/pkg/services/reputation/common"
 
 	"github.com/nspcc-dev/neofs-node/pkg/services/reputation"
 )
@@ -20,7 +19,7 @@ func (ctx *EpochContext) Epoch() uint64 {
 
 type NopReputationWriter struct{}
 
-func (NopReputationWriter) Write(common.Context, reputation.Trust) error {
+func (NopReputationWriter) Write(reputation.Trust) error {
 	return nil
 }