IR codegen does not implement access to library address by contract name

Discovered in https://github.com/ethereum/solidity/pull/15661#discussion_r1894361095

## Description

A reference to a library name in inline assembly triggers an unimplemented feature error. At this point the IR codegen is considered feature-complete so this not being implemented yet is a bug.

Moreover the error does not provide any message for the user.

While we do have this case covered by a syntax test ([`assignment_from_library.sol`](https://github.com/ethereum/solidity/blob/develop/test/libsolidity/syntaxTests/inlineAssembly/assignment_from_library.sol)), it went undiscovered until now because we don't run syntax tests via IR. When the bug is fixed, please remember to enable this test on EOF.

## Environment

- Compiler version: 0.8.28 (`develop`)

## Steps to Reproduce

`test.sol`:
```solidity
library L {}

contract C {
function f() public pure {
assembly {
let x := L
}
}
}
```
```bash
solc test.sol --ir
```
```
Error: Unimplemented feature
--> test.sol:5:9:
|
5 | assembly {
| ^ (Relevant source part starts here and spans across multiple lines).
```

Start with test/libsolidity/syntaxTests/inlineAssembly/assignment_from_library.sol and reproduce the issue using solc test.sol --ir. Trace the IR codegen path for an inline-assembly library reference; done means the reference is handled without an unimplemented-feature failure, the user receives a message, and the syntax test is enabled on EOF.

Written by the indexing model from the issue text.