[Application] Add min_stake application module param (#845)

## Summary

- Adds the `min_stake` application module param.
- Adds missing validation unit test coverage around existing application
module param, `max_delegated_gateways`.
- Pushes validation from the `MsgUpdateParam` handler down into
`MsgUpdateParam#ValidateBasic()`.
- Ensures `Params#Valid()` is called prior to setting params in
`MsgUpdateParam` handler.
- Updates error returns in the same handler to ensure all error paths
return appropriate gRPC status errors.

## Dependencies

- #809
- #843 
- #844 

## Dependents

- #847 
- #848 
- #849
- #850
- #857

## Issue

- #612

## Type of change

Select one or more from the following:

- [x] New feature, functionality or library
- [x] Consensus breaking; add the `consensus-breaking` label if so. See
#791 for details
- [ ] Bug fix
- [ ] Code health or cleanup
- [ ] Documentation
- [ ] Other (specify)

## Testing

- [ ] **Documentation**: `make docusaurus_start`; only needed if you
make doc changes
- [ ] **Unit Tests**: `make go_develop_and_test`
- [ ] **LocalNet E2E Tests**: `make test_e2e`
- [ ] **DevNet E2E Tests**: Add the `devnet-test-e2e` label to the PR.

## Sanity Checklist

- [ ] I have tested my changes using the available tooling
- [ ] I have commented my code
- [ ] I have performed a self-review of my own code; both comments &
source code
- [ ] I create and reference any new tickets, if applicable
- [ ] I have left TODOs throughout the codebase, if applicable

---------

Co-authored-by: Redouane Lakrache <[email protected]>
Co-authored-by: Daniel Olshansky <[email protected]>
Co-authored-by: red-0ne <[email protected]>