fix: correct csms_leaf_cert_directory default value in EvseSecurity

[cakira]

Describe your changes

This pull request fixes a bug that impeded me from connecting to a CSMS server with OCPP Profile 3.

The csms_leaf_cert_directory should point to the directory where CSMS
leaf certificates are stored. However, the current default value
(client/csms) does not reflect the actual location. The certificates
are placed in ca/csms by the script
Josev/iso15118/shared/pki/create_certs.sh.

The directory certs/ca/csms/ contains:
  - CPO_SUB_CA1.pem
  - CPO_SUB_CA1_LEAF.der
  - CPO_SUB_CA2.pem
  - CPO_SUB_CA2_LEAF.der

Meanwhile, certs/client/csms/ is used to store the private keys:
  - CPO_SUB_CA1.key
  - CPO_SUB_CA2.key

This commit updates the default value of csms_leaf_cert_directory in
EvseSecurity to ca/csms, to match the directory structure created by
the script.

Issue ticket number and link

None

Checklist before requesting a review

• I have performed a self-review of my code
• I have made corresponding changes to the documentation
• I read the contribution documentation and made sure that my changes meet its requirements

[cakira]

In the same file (modules/EvseSecurity/manifest.yaml), it seems that secc_leaf_cert_directory default value should also be changed, from client/cso to ca/cso.

However, I decided not to change it because I don’t know how to test it yet.

[AssemblyJohn]

This issue seems to be more related to the cert generation and config (which is modifiable by end-users anyway) and this PR should fix it in an attempted cleaner manner: #399

Further modifications should be done in that PR.