Add support for transient keyword

[zerosnacks]

Request

0.8.28 introduced the transient keyword in Solidity: https://soliditylang.org/blog/2024/10/09/solidity-0.8.28-release-announcement/

Context

Foundry uses Solang's parser for its formatter, see foundry-rs/foundry#9088

[zerosnacks]

ping @ryjones / @seanyoung, would be great to get support for this

[ryjones]

@zerosnacks I do backend stuff, not code, but I've added the right people

[zerosnacks]

@zerosnacks I do backend stuff, not code, but I've added the right people

Thanks! I appreciate it

[seanyoung]

I just need to find some time to add this feature to the parser - should be straightforward.

[seanyoung]

So I had a look at this - it's not so simple. The way this is added to solc is that there is no new keyword. For example:

contract C {
	uint transient transient;
}

is allowed. We need to figure out how to add this without adding a new keyword.