Create notes without assets

[Dominik1999]

We started exploring this idea during a discussion with @nlok5923.

Right now, notes are designed to transfer assets between accounts. There can be scenarios where a note can be transferred without assets.

For example, in current use case we want to change state of a game account directly based on the actions of a player account. In such scenario, the player account can send a note to the game account where the game account will authenticate the player account with its signature and updates it state and hence does not have a necessity for the note to store/transfer assets. Likewise, there can be more similar scenarios where such a feature can provide an easy and better way of utilizing notes.

Originally posted by @gubloon in #558

Implementation idea

First, this check needs to be removed (I would allow an empty vector of assets)

miden-base/objects/src/notes/assets.rs

Lines 41 to 43 in 7ab15df

	pub fn new(assets: Vec<Asset>) -> Result<Self, NoteError> {
	if assets.is_empty() {
	return Err(NoteError::EmptyAssetList);

Maybe we need to change something in the kernel / prologue here (at a first look, we don't need to)

miden-base/miden-lib/asm/miden/kernels/tx/prologue.masm

Line 659 in 7ab15df

# ingest note assets

Maybe also in the epilogue (but also here, that should already work with 0 assets)

https://github.com/0xPolygonMiden/miden-base/blob/7ab15dff526f0626daa0aae188787fb4bb45dcc9/miden-lib/asm/miden/kernels/tx/epilogue.masm#L253C18-L253C38

[bobbinth]

Closed by #686.