fix: address compiler warnings

[adamegyed]

Motivation

We have two small compiler warnings in our current code on develop:

• SPDX license identifier not provided in source file. ... in DirectCallsFromModule.t.sol

• Warning (5740): Unreachable code.
    --> src/account/AccountStorageInitializable.sol:49:9:
     |
  49 |         if (isTopLevelCall) {
     |         ^ (Relevant source part starts here and spans across multiple lines).
  

Solution

Add an SPDX identifier to the test file.

Remove the initializer modifier from the overwritten initializer function in SemiModularAccount, and reorder functions due to the new pure visibility.

[Zer0dot]

Thanks for this!