bugfixes

### Feature or Bugfix
<!-- please choose -->
- When MF enforcement rule is created, entity owners are notified
asynchronously. MF enforcement rule is created and return immidiately
- fix for delete_mf_enforcement_rule
- small typos


### Detail
- <feature1 or bug1>
- <feature2 or bug2>

### Relates
- <URL or Ticket>

### Security
Please answer the questions below briefly where applicable, or write
`N/A`. Based on
[OWASP 10](https://owasp.org/Top10/en/).

- Does this PR introduce or modify any input fields or queries - this
includes
fetching data from storage outside the application (e.g. a database, an
S3 bucket)?
  - Is the input sanitized?
- What precautions are you taking before deserializing the data you
consume?
  - Is injection prevented by parametrizing queries?
  - Have you ensured no `eval` or similar functions are used?
- Does this PR introduce any functionality or component that requires
authorization?
- How have you ensured it respects the existing AuthN/AuthZ mechanisms?
  - Are you logging failed auth attempts?
- Are you using or adding any cryptographic features?
  - Do you use a standard proven implementations?
  - Are the used keys controlled by the customer? Where are they stored?
- Are you introducing any new policies/roles/users?
  - Have you used the least-privilege principle? How?


By submitting this pull request, I confirm that my contribution is made
under the terms of the Apache 2.0 license.

---------

Co-authored-by: Sofia Sazonova <sazonova@amazon.co.uk>
Co-authored-by: Petros Kalos <kalosp@amazon.com>