feat: Add summary option

[Jason3S]

  summary:
    description: |
      Include a summary of the results in the output.
      Allowed values are: "true", "false"
    default: 'false'
    required: false

Example output:

CSpell Summary

• Files checked: 4
• Issues found: 2
• Files with issues: 1
• Files skipped: 1

[coveralls]

Pull Request Test Coverage Report for Build 20102077489

Details

• 20 of 20 (100.0%) changed or added relevant lines in 4 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-1.1%) to 94.601%

---

Totals
Change from base Build 20098729524:	-1.1%
Covered Lines:	256
Relevant Lines:	261

---

💛 - Coveralls