Bugs Related to Dimensions

Although the specification should be such that dimensions greater than 1,000 are not visible from the 0-dimensional view, on the stream side (for data retrieved automatically), 0 is treated as `null` and processed as if there were no dimension filter, so it appears that dimensions greater than 1,000 are visible.

It appears that the cause is the `normalizeDimension()` function in `misskey/packages/backend/src/misc/dimension.ts`, which sets dimensions of 0 or lower to `null`. However, since this function is also used to set the 0th dimension to `null` (dimension not set) when a post is made, it might be safer to ensure that only the view dimension for streams is treated as a valid value of 0 in files such as `misskey/packages/backend/src/server/api/stream/channel.ts and similar files to ensure that only 0 is treated as a valid value for the stream’s viewing dimension.