Implement filter for Task Owners

[kokerinks]

Summary:

In this context, we define a Task owner as follows:

• For an issue, task owner refers to the members assigned that issue
• For a pull request, task owner refers to the author/creator of the PR

Fixes #342

Type of change:

• ✨ New Feature/ Enhancement

Changes Made:

• Implemented a new filter which filters issues/PRs based on a Task Owner, i.e.:
  • Author/creator for PRs
  • Assignees for issues

Screenshots:

Proposed Commit Message:

Implement filter for Task Owners

Having a function to filter issues/PRs by task owners can 
give users a more organised overview of the contributions
made by each member in the project. 

Hence, let's add it to the list of existing filters we have 
currently for users.

Checklist:

• I have tested my changes thoroughly.
• I have created tests for any new code files created in this PR or provided a link to a issue/PR that addresses this.
• I have added or modified code comments to improve code readability where necessary.
• I have updated the project's documentation as necessary.

[NereusWB922]

Hi, just one minor comment. Other than that, everything look good.

[NereusWB922]

LGTM

[NereusWB922]

@kokerinks Approved. You can merge it when you are ready

[kokerinks]

@NereusWB922 can you help to merge this please? I dont have enough write access :')