CSUB-899: Add pallet_scheduler

[zacharyfrederick]

Description of proposed changes

---

Practical tips for PR review & merge:

• All GitHub Actions report PASS
• Newly added code/functions have unit tests
  • Coverage tools report all newly added lines as covered
  • The positive scenario is exercised
  • Negative scenarios are exercised, e.g. assert on all possible errors
  • Assert on events triggered if applicable
  • Assert on changes made to storage if applicable
• Modified behavior/functions - try to make sure above test items are covered
• Integration tests are added if applicable/needed

[github-actions]

For full LLVM coverage report click here!

[atodorov]

Let's exercise this functionality during runtime upgrades for Devnet, see
https://github.com/gluwa/creditcoin3/blob/dev/.github/workflows/wasm.yml#L81

Replace 0 with any other positive integer (doesn't need to be 50 IMO, can be something as low as 5).

[atodorov]

Commit to typedefs failed, https://github.com/gluwa/creditcoin3/actions/runs/7491379520/job/20392737262.

I think if you drop the existing automated commits and rebase the PR so that CI jobs execute again it will fix itself.

[atodorov]

FTR rebased onto latest dev, dropped automated commits (will be regenerated) and squashed the first 2. Will approve and merge once CI jobs are passing.

[atodorov]

Tests passing for 75adbff. llvm-cov failure is a known one, needs update to Azure credentials.

Merging this PR.