Notify exsting users with invite

[TimCsaky]

For the share feature, also notify existing users where result is just a permission update.

Description

ticket: https://apps.nrs.gov.bc.ca/int/jira/browse/SHOWCASE-3702
For the share feature, also notify existing users where result is just a permission update.

Types of changes

New feature (non-breaking change which adds functionality)

Checklist

• I have read the CONTRIBUTING doc
• I have checked that unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

Further comments

[github-actions]

Coverage Report (Application)

Totals
Statements:	70.67% ( 53 / 75 )
Methods:	62.5% ( 5 / 8 )
Lines:	81.63% ( 40 / 49 )
Branches:	44.44% ( 8 / 18 )

[github-actions]

Coverage Report (Frontend)

Totals
Statements:	18.06% ( 754 / 4174 )
Methods:	17.82% ( 139 / 780 )
Lines:	22.27% ( 532 / 2389 )
Branches:	8.26% ( 83 / 1005 )

[codeclimate]

Code Climate has analyzed commit 2ad312f and detected 5 issues on this pull request.

Here's the issue category breakdown:

Category	Count
Complexity	1
Duplication	4

The test coverage on the diff in this pull request is 4.2% (50% is the threshold).

This pull request will bring the total coverage in the repository to 23.4% (-0.3% change).

View more on Code Climate.