Isolate rhp2 worker code into rhp2 client (#1440)

This PR refactors 2 things:

1. rhp2 code is moved to `internal` into a `Client`
2. gouging code is moved to `internal` to be able to pass gouging
checkers to client

This is a preparation for when the bus also needs access to rhp clients
and gouging code.

autopilot/contractor/evaluate.go

@@ -5,13 +5,13 @@ import (
 
 	"go.sia.tech/core/types"
 	"go.sia.tech/renterd/api"
-	"go.sia.tech/renterd/worker"
+	"go.sia.tech/renterd/internal/gouging"
 )
 
 var ErrMissingRequiredFields = errors.New("missing required fields in configuration, both allowance and amount must be set")
 
 func countUsableHosts(cfg api.AutopilotConfig, cs api.ConsensusState, fee types.Currency, period uint64, rs api.RedundancySettings, gs api.GougingSettings, hosts []api.Host) (usables uint64) {
-	gc := worker.NewGougingChecker(gs, cs, fee, period, cfg.Contracts.RenewWindow)
+	gc := gouging.NewChecker(gs, cs, fee, &period, &cfg.Contracts.RenewWindow)
 	for _, host := range hosts {
 		hc := checkHost(gc, scoreHost(host, cfg, rs.Redundancy()), minValidScore)
 		if hc.Usability.IsUsable() {
@@ -31,7 +31,7 @@ func EvaluateConfig(cfg api.AutopilotConfig, cs api.ConsensusState, fee types.Cu
 	}
 
 	period := cfg.Contracts.Period
-	gc := worker.NewGougingChecker(gs, cs, fee, period, cfg.Contracts.RenewWindow)
+	gc := gouging.NewChecker(gs, cs, fee, &period, &cfg.Contracts.RenewWindow)
 
 	resp.Hosts = uint64(len(hosts))
 	for i, host := range hosts {

autopilot/contractor/hostfilter.go

@@ -10,7 +10,7 @@ import (
 	rhpv3 "go.sia.tech/core/rhp/v3"
 	"go.sia.tech/core/types"
 	"go.sia.tech/renterd/api"
-	"go.sia.tech/renterd/worker"
+	"go.sia.tech/renterd/internal/gouging"
 )
 
 const (
@@ -220,7 +220,7 @@ func isUpForRenewal(cfg api.AutopilotConfig, r types.FileContractRevision, block
 }
 
 // checkHost performs a series of checks on the host.
-func checkHost(gc worker.GougingChecker, sh scoredHost, minScore float64) *api.HostCheck {
+func checkHost(gc gouging.Checker, sh scoredHost, minScore float64) *api.HostCheck {
 	h := sh.host
 
 	// prepare host breakdown fields

autopilot/contractor/state.go

@@ -7,7 +7,7 @@ import (
 
 	"go.sia.tech/core/types"
 	"go.sia.tech/renterd/api"
-	"go.sia.tech/renterd/worker"
+	"go.sia.tech/renterd/internal/gouging"
 )
 
 type (
@@ -73,8 +73,9 @@ func (ctx *mCtx) Err() error {
 	return ctx.ctx.Err()
 }
 
-func (ctx *mCtx) GougingChecker(cs api.ConsensusState) worker.GougingChecker {
-	return worker.NewGougingChecker(ctx.state.GS, cs, ctx.state.Fee, ctx.Period(), ctx.RenewWindow())
+func (ctx *mCtx) GougingChecker(cs api.ConsensusState) gouging.Checker {
+	period, renewWindow := ctx.Period(), ctx.RenewWindow()
+	return gouging.NewChecker(ctx.state.GS, cs, ctx.state.Fee, &period, &renewWindow)
 }
 
 func (ctx *mCtx) HostScore(h api.Host) (sb api.HostScoreBreakdown, err error) {