Add Gosec Security Scan

[KKelvinLo]

Motivation

This PR is a follow-up to issue open-telemetry/oteps#144

GoSec is a static analysis engine which scans repos for security vulnerabilities. As the project grows and we near GA it might be useful to have a workflow which checks for security vulnerabilities to ensure that every incremental change is following best development practices. Also passing basic security checks will also make sure that there aren't any glaring issues for our users.

Changes

• This PR adds GoSec security checks to the repository. Details on the run and security alerts will show up in the security tab of this repo.

Workflow Triggers

• daily cron job at 1:30 am
• workflow_dispatch (in the case that the maintainers want to trigger a manual security check)