Add initCommands to Vault Dev Services configuration

[kdubb]

Allows custom vault commands to be run on dev services container startup.

[vsevel]

LGTM.
I do not see any test.
@geoand that is not possible to have integration testing on dev services?
I searched through the codebase, and found only one occurence of quarkus.XX.devservices.enabled=true in all the integration tests (it is in quarkus-integration-test-micrometer-prometheus).
in this particular case, I see the withInitCommand has already been used for the transit and pki engines init. so we will be fine. but just wondering. what is the expected level of testing for devservices?

[geoand]

Dev Services are enabled by default, so plenty of integration tests use them, for example https://github.com/quarkusio/quarkus/blob/2.4.1.Final/integration-tests/mongodb-rest-data-panache/pom.xml

[kdubb]

As far as I remember (I could be wrong) Vault ITs don't use dev services currently. So, I was being a bit lazy and didn't want to devise a whole new test scheme for this two line addition 😏