feat (clientcache): use a persistent cache (#5051)

By default, we will use a persistent cache for the
client cache. This will allow us to keep the cache
across restarts of the server and it will also
reduce the amount of time it takes to start the
server while reducing the amount of memory used.

This change also includes a validation of the cache
schema version. If the schema version is different
from the one expected, the cache will be
reset/recreated.

(cherry picked from commit cf8a51f3834033b7f986a9a7e091ab31c4328415)

internal/clientcache/cmd/cache/start.go

@@ -19,7 +19,6 @@ import (
 	"github.com/hashicorp/boundary/internal/cmd/base"
 	"github.com/hashicorp/boundary/internal/errors"
 	"github.com/mitchellh/cli"
-	"github.com/mitchellh/go-homedir"
 	"github.com/posener/complete"
 	"gopkg.in/natefinch/lumberjack.v2"
 )
@@ -243,7 +242,7 @@ func (c *StartCommand) Run(args []string) int {
 // DefaultDotDirectory returns the default path to the boundary dot directory.
 func DefaultDotDirectory(ctx context.Context) (string, error) {
 	const op = "cache.DefaultDotDirectory"
-	homeDir, err := homedir.Dir()
+	homeDir, err := os.UserHomeDir()
 	if err != nil {
 		return "", errors.Wrap(ctx, err, op)
 	}