[feature] User muting (#2960)

* User muting

* Address review feedback

* Rename uniqueness constraint on user_mutes to match convention

* Remove unused account_id from where clause

* Add UserMute to NewTestDB

* Update test/envparsing.sh with new and fixed cache stuff

* Address tobi's review comments

* Make compiledUserMuteListEntry.expired consistent with UserMute.Expired

* Make sure mute_expires_at is serialized as an explicit null for indefinite mutes

---------

Co-authored-by: tobi <tobi.smethurst@protonmail.com>

internal/cache/size.go

@@ -715,3 +715,15 @@ func sizeofUser() uintptr {
 		ExternalID:             exampleID,
 	}))
 }
+
+func sizeofUserMute() uintptr {
+	return uintptr(size.Of(&gtsmodel.UserMute{
+		ID:              exampleID,
+		CreatedAt:       exampleTime,
+		UpdatedAt:       exampleTime,
+		ExpiresAt:       exampleTime,
+		AccountID:       exampleID,
+		TargetAccountID: exampleID,
+		Notifications:   util.Ptr(false),
+	}))
+}