feat(toaster) : #MAG-264 add button to notify other users of board

[FlorentMr]

Describe your changes

Add a button to all manager and owner so they can notify (in the timeline) other users of that board that a modification was made.

Checklist tests

cf ticket

Issue ticket number and link

MAG-264

Checklist before requesting a review (magic string, indentation, comment/documentation...)

• I have detailed the tests to do in my feature/fix in order to prevent consequents regressions (must specify in Checklist tests)
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (API Doc etc...) - (must specify in Description for target version)
• If it is a consequent feature, I have added thorough tests.
• I have added tests that prove my fix is effective or that my feature works
• Any dependent changes have been added to this project (must specify in Description)