fix: update Target.isTagged to exclude optional

[notaphplover]

Description

A binding with optional decorator should not be considered tagged just for that fact.
This PR adds optional to the list of decorators to exclude in order to determine whether or not a binding is tagged.

Related Issue

#1190

Motivation and Context

This change allow to determine wheter or not a binding is tagged and avoid unexpected behavior such as the one described in the related issue.

How Has This Been Tested?

• Tests has been added to cover the issue behavior

Types of changes

• Updated docs / Refactor code / Added a tests case (non-breaking change)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.
• I have updated the changelog.

[dcavanagh]

LGTM