NetworkController upgrade from v19 to v20

### What is this about?

The `NetworkController` is behind by two major versions and needs to be updated.
Upgrade from v19 to v21.
Additionally, there are several peer dependencies which will likely be best to be upgraded at the same time. Those are the following:

- `GasFeeController` is on 18 should be on 20
- `TransactionsController` v 35 should be v36

### Scenario

n/a

### Design

n/a

### Technical Details

n/a

### Threat Modeling Framework

n/a

### Acceptance Criteria

- `NetworkController` is on v21
- `GasFeeController` is on v20
- `TransactionsController` is on v36

### Stakeholder review needed before the work gets merged

- [X] Engineering (needed in most cases)
- [ ] Design
- [ ] Product
- [ ] QA (automation tests are required to pass before merging PRs but not all changes are covered by automation tests - please review if QA is needed beyond automation tests)
- [ ] Security
- [ ] Legal
- [ ] Marketing
- [ ] Management (please specify)
- [ ] Other (please specify)

### References

_No response_

Start by locating the NetworkController, GasFeeController, and TransactionsController version declarations in the repository's dependency or package configuration. Check how related controller versions are coordinated and run the existing automation tests. Done means NetworkController is v21, GasFeeController is v20, and TransactionsController is v36.

Written by the indexing model from the issue text.