ENH Add `$startIndex` param to `Pos` method

[nedmas]

Description

I've added $startIndex param to the Pos method with a default value of 1.

Manual testing steps

Loop through elements in an elemental area and print the results of $Pos(1).

Issues

• 1221

Pull request checklist

• [*] The target branch is correct
  • See picking the right version
• [*] All commits are relevant to the purpose of the PR (e.g. no debug statements, unrelated refactoring, or arbitrary linting)
  • Small amounts of additional linting are usually okay, but if it makes it hard to concentrate on the relevant changes, ask for the unrelated changes to be reverted, and submitted as a separate PR.
• [*] The commit messages follow our commit message guidelines
• [*] The PR follows our contribution guidelines
• [*] Code changes follow our coding conventions
• [*] This change is covered with tests (or tests aren't necessary for this change)
• [*] Any relevant User Help/Developer documentation is updated; for impactful changes, information is added to the changelog for the intended release
• [*] CI is green

[michalkleiner]

Just curious @nedmas, based on what did you check the CI is green item in the checklist? The CI for this PR hasn't run yet.

[nedmas]

Just curious @nedmas, based on what did you check the CI is green item in the checklist? The CI for this PR hasn't run yet.

So honestly I just marked it complete because I got overwhelmed by the amount of stuff I was required to read/do just to add a minor PR. Tried my best but I guess I got it wrong :smiley: Out of interest what should I have done? So I know for next time.