Set and Clear Collection Metadata

[HashWarlock]

Request to add similar functions that exists for Uniques pallet to set/clear metadata for a NFT Collection with functions set_collection_metadata and clear_collection_metadata.

set_collection_metadata
https://github.com/paritytech/substrate/blob/6e52d60931e4398b8a974a0966821f5e27481b8b/frame/uniques/src/lib.rs#L1324-L1366

clear_collection_metadata
https://github.com/paritytech/substrate/blob/6e52d60931e4398b8a974a0966821f5e27481b8b/frame/uniques/src/lib.rs#L1382-L1405

[Szegoo]

@HashWarlock are you working on this or is this free to work on?

[HashWarlock]

@HashWarlock are you working on this or is this free to work on?

Free to work on now if you'd like to add the functionality.

[Szegoo]

I am busy at the moment with some other PRs, so I might work on this in the future if in the meantime you or someone else doesn't open a PR.