chore: add optimized-build profile

[jaypaik]

Adding this profile so we can run faster local size checks (~10s on my machine) on IR builds.
More work on foundry.toml (and the README) to come later. This is to unblock us quickly.

Usage:

❯ FOUNDRY_PROFILE=optimized-build forge b --sizes
[⠊] Compiling...
[⠒] Compiling 73 files with 0.8.21
[⠑] Solc 0.8.21 finished in 9.91s
Compiler run successful!
| Contract                           | Size (kB) | Margin (kB) |
|------------------------------------|-----------|-------------|
| AccountStorageV1                   | 0.058     | 24.518      |
| Address                            | 0.058     | 24.518      |
| AssociatedLinkedListSetLib         | 0.058     | 24.518      |
| CastLib                            | 0.058     | 24.518      |
| CountableLinkedListSetLib          | 0.058     | 24.518      |
| Create2                            | 0.058     | 24.518      |
| ECDSA                              | 0.058     | 24.518      |
| ERC165Checker                      | 0.058     | 24.518      |
| ERC1967Proxy                       | 0.209     | 24.367      |
| FunctionReferenceLib               | 0.058     | 24.518      |
| KnownSelectors                     | 0.058     | 24.518      |
| LinkedListSetLib                   | 0.058     | 24.518      |
| Math                               | 0.058     | 24.518      |
| MultiOwnerMSCAFactory              | 5.264     | 19.312      |
| MultiOwnerPlugin                   | 8.419     | 16.157      |
| MultiOwnerTokenReceiverMSCAFactory | 5.467     | 19.109      |
| PluginStorageLib                   | 0.058     | 24.518      |
| SafeERC20                          | 0.058     | 24.518      |
| SessionKeyPermissionsPlugin        | 9.74      | 14.836      |
| SessionKeyPlugin                   | 7.306     | 17.27       |
| ShortStrings                       | 0.058     | 24.518      |
| SignatureChecker                   | 0.058     | 24.518      |
| SignedMath                         | 0.058     | 24.518      |
| StorageSlot                        | 0.058     | 24.518      |
| Strings                            | 0.058     | 24.518      |
| TokenReceiverPlugin                | 3.419     | 21.157      |
| UpgradeableModularAccount          | 24.338    | 0.238       |

[fangting-alchemy]

Looks good. Can we add usage instructions into readme?

[adam-alchemy]

Looks good, saw the comment about adding the test harness later. I think it's good that this keeps the default profile as IR, too. Also it's probably worth adding the build with sizes command to the readme as Fangting mentioned.