feat/json reports

[zeroXbrock]

Motivation

preparing for report data to be used in automated reports & analysis

Solution

• add --format to reports to enable contender report to generate JSON instead of HTML
• add global --data-dir flag to control contender's data location (helpful for CI)

PR Checklist

• Added Tests
• Added Documentation
• Ran cargo +nightly clippy --workspace --lib --examples --tests --benches --all-features --locked --fix
• Ran cargo fmt --all
• Note breaking changes in PR description, if applicable
• update changelogs
  • Update CHANGELOG.md in each affected crate
  • add a high-level description in the root changelog