Keep assets from bpmn-js-token-simulation in sync

[Do-min-ik]

Which issue does this PR address?

Closes #18

I added a webpack copy plugin in order to copy bpmn-js-token-simulation's assets into bpmn-js-token-simulation-plugin's folder. If we don't do that we may miss changes to stylesheets and fonts.

Acceptance Criteria

• [x] Corresponds to the concept
• [x] Corresponds to the design

Definition of Done

• [x] corresponds to the design principles
• [x] corresponds to the code standards
• [x] passes Continuous Integration checks
• [x] available as feature branch on GitHub
  • [x] contains the cleaned up commit history
  • [x] commit messages satisfy our commit message guidelines
  • [x] a single commit closes the issue via Closes #issuenr

[CLAassistant]

All committers have signed the CLA.

[pinussilvestrus]

Thanks a lot! Can we maybe have one single commit to fix the issue?

fix: copy assets from bpmn-js-token-simulation

Closes #18

[nikku]

Sorry for the delay in responding.

Thanks again for your contribution. Merged via https://github.com/bpmn-io/bpmn-js-token-simulation-plugin/commit/cb0c8bd38f11c426180336eea1cbfdd40fdc54b5, released as v0.10.1 :tada: :package:.