Remove action is not cancellable on Role assignment screen

[dtaimanov]

Steps:

1. Create single module application using template
2. Open Users -> Role assignments
3. Remove some role assignment and press "Cancel" button
4. Open Role assignments screen again

ER:

• deletion of role assignment is cancelled and it is present in table

AR:

• Role assignment removed

At the same time creation of Role assignment can be successfully cancelled

Additional:

fix the same situation on user substitution screen

[gorbunkov]

Commit: https://github.com/Haulmont/jmix-security/commit/124bdad9159549fa6b674dca80c3443331a9490e

[konyashkina]

Tested on Jmix version: 1.1.0-SNAPSHOT Jmix Studio plugin version: 1.1.SNAPSHOT3600-212 IntelliJ version: IntelliJ IDEA 2021.2.2 (Ultimate Edition)

• [x] Role assignments screen
• [x] User substitutions screen