Add publish workflow for snforge_scarb_plugin

[THenry14]

Which components does the task require to be changed? (think hard pls)

other (describe below)

Description

Related to #2344

Under said issue automatic uploads for snforge_std and sncast_std was added. At the time of creating relevant PRs there was still no support for scarb package for procmacros. The aim of this issue is to update the publish workflow, to also automatically upload new snforge_scarb_plugin whenever its version changes. This could probably be a separate publish flow for each push to master, where crates/snforge_scarb_plugin/Scarb.toml is changed and its version is not already deployed to the registry.

Blocked by software-mansion/scarb#1527

Up until now, whenever a new version of snforge_scarb_plugin is needed please construct the package manually. If needed, seek help from scarb team.