## Summary
Allowed the config to not have nodes, links and agents and still be parsed
## Test process
Tested with config file that doesn't have any simulation key/value pair
## Checklist
- [X] PR is linked to a **work item**
- [X] **acceptance criteria** of linked ticket are met
- [X] performed **self-review** of the code
- [X] written **tests** for any new functionality added with this PR
- [ ] updated the **documentation** if this PR changes or adds functionality
- [ ] written/updated **design docs** if this PR implements new functionality
- [ ] updated the **change log**
- [X] ran **pre-commit** checks for code style
- [ ] attended to any **TO-DOs** left in the code
#2357 - Allowed the config to not have nodes, links and agents and still be parsed
Related work items: #2357
- Enhance NicObservation for detailed NMNE event monitoring.
- Add nmne_config options to simulation settings for customizable NMNE capturing.
- Update documentation and tests for new NMNE features and simulation config.
## Summary
- Added ability to set DoSBot in nodes via config file
- Fixed missing configuration items in other services/applications
- Created a variable which contains the list of applications and services
- Moved `DatabaseClient` from list of services to list of applications
## Test process
Created a configuration file where a node has all services and applications installed, this is then used by an integration test which loads the configuration file. The test checks to make sure that the configuration file is correctly read and the Service and Application objects are properly created
## Checklist
- [X] PR is linked to a **work item**
- [ ] **acceptance criteria** of linked ticket are met
- [X] performed **self-review** of the code
- [X] written **tests** for any new functionality added with this PR
- [ ] updated the **documentation** if this PR changes or adds functionality
- [ ] written/updated **design docs** if this PR implements new functionality
- [ ] updated the **change log**
- [ ] ran **pre-commit** checks for code style
- [ ] attended to any **TO-DOs** left in the code
Related work items: #2258
