Proposed changes

Support changing the pkcs11 client key uri without requiring a restart of the tedge-p11-server.
Call C_Initialize again so C_GetSlotList returns updated slot list.

• Test
• Fix

PR should be rebased after #3771 is merged

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Improvement (general improvements like code refactoring that doesn't explicitly fix a bug or add any new functionality)
• Documentation Update (if none of the other choices apply)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Paste Link to the issue

#3766

Checklist

• I have read the CONTRIBUTING doc
• I have signed the CLA (in all commits with git commit -s. You can activate automatic signing by running just prepare-dev once)
• I ran just format as mentioned in CODING_GUIDELINES
• I used just check as mentioned in CODING_GUIDELINES
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

Further comments

According to PKCS #11 Version 2.40 Specification, Section 5.5 C_GetSlotList:

[...] If an application calls C_GetSlotList with a non-NULL pSlotList, and then the user adds or removes a hardware device, the changed slot list will only be visible and effective if C_GetSlotList is called again with NULL. Even if C_ GetSlotList is successfully called this way, it may or may not be the case that the changed slot list will be successfully recognized depending on the library implementation. On some platforms, or earlier PKCS11 compliant libraries, it may be necessary to successfully call C_Initialize or to restart the entire system.

In our case, SoftHSM2 is an example of such a library:

1. C_GetSlotList calls slotManager.getSlotList()
2. getSlotList reads from slots
3. slots is initialized in the constructor
4. SlotManager is created when C_Initialize is called

The disadvantage of that approach is we have to call dlopen again, per request, and in some environments this can be very slow apparently, but unless we can empirically confirm that this poses a problem, we'll proceed with this. Other libraries may be more reasonable and refresh the list on C_GetSlotList length request, as the spec suggests, but as we primarily develop and test against SoftHSM2, we'll proceed with this for now.