[Bug]: Invalid type assigned to literals

[Shungy]

Describe the issue:

It appears that IR considers literals as uint256 or int256 type, but they should be assigned the smallest possible type instead.

Code example to reproduce the issue:

	function test5(uint40 x) external view returns (uint256 res) {
		res = x * 50;
	}

50 should be uint8, but ir.variable_right.type returns uint256.

Version:

0.9.2

Relevant log output:

No response

[0xalpharush]

There currently is consistent support for the implicit type conversions #284. We should try to reach parity with Solidity so we can have detectors for unsafe casts