fix(contracts): OZ-N02 Incorrect Function Visibility

[zimpha]

Purpose or design rationale of this PR

This PR partially fixed the issue reported by Openzepplin (N-02 Incorrect Function Visibility) during ScrollOwner and Rate Limiter audit. The following are the details:

In the ScrollOwner contract, the execute function is marked as public, while the _execute function has internal visibility.

The execute function should be marked as external because it is not called internally by any of the functions in the ScrollOwner contract.

The _execute function should be marked as private because it is implemented in the top-level ScrollOwner contract and is not intended to be called by the derived contracts. To improve the overall clarity, intent, and readability of the codebase, consider fixing the visibility for these functions.

PR title

Your PR title must follow conventional commits (as we are doing squash merge for each PR), so it must start with one of the following types:

• fix: A bug fix

Deployment tag versioning

Has tag in common/version.go been updated or have you added bump-version tag to this PR?

• No, this PR doesn't involve a new deployment, git tag, docker image tag
• Yes

Breaking change label

Does this PR have the breaking-change label?

• No, this PR is not a breaking change
• Yes

[github-actions]

LCOV of commit e780334 during Contracts #1370

Summary coverage rate:
  lines......: 52.6% (992 of 1885 lines)
  functions..: 67.3% (222 of 330 functions)
  branches...: no data found

Files changed coverage rate: n/a