feat(wallet): add existence check for wallet creation

[Phil91]

Description

• adjust api Post: api/dim/setup-dim to include an existence check for companyName and bpn, if an entry already exists an exception is thrown

Why

When trying to create the wallet with the same key "company_name"_"bpn" the wallet creation will fail, therefore the check of existence is added in the api

Issue

Refs: #66

Checklist

• I have performed a self-review of my own code
• I have successfully tested my changes locally
• I have added tests that prove my changes work
• I have checked that new and existing tests pass locally with my changes
• I have commented my code, particularly in hard-to-understand areas
• I have added copyright and license headers, footers (for .md files) or files (for images)

[evegufy]

@Phil91 thanks for the change.
I'd like to get the patch version finalized for the 1.2.0 version before merging another feature as this should be properly tested and part of a minor version.