[Monorepo] PR "move" and wrapping up

[pkra]

To wrap up the monorepo move, please complete the following:

• review PRs (see link list below)
  • close PRs that were "moved" correctly
  • handle PRs from forks (which could not be "moved" the same way)
    • either alert authors to make new PRs to on the ARIA repository and close the PR
    • or (to maintain a useful diff) create a branch (e.g., "old_main") and change those PRs to target that branch
• merge "closing" PR Editorial: Move this spec to ARIA monorepo #548

PR list

• Clarify li element role mapping #540 => [html-aam PR 540] Clarify li element role mapping aria#2212
• add obsolete dir element #539 => [html-aam PR 539] add obsolete dir element aria#2213
• Specify AXAPI behaviour for low, high, and optimum meter attributes. #538 => TODO (from fork)
• Clarify hidden elements do not return name #533 => [html-aam PR 533] Clarify hidden elements do not return name aria#2214
• Addition: Name from heading #529 => [html-aam PR 529] Addition: Name from heading aria#2215
• feat: add IA2 and ATK mappings for text edit maxlength #522 => TODO (from fork)
• feat: add UIA mappings for text edit maxlength #521 => TODO (from fork)
• UA ignore aria-hidden on root elements #516 => [html-aam PR 516] UA ignore aria-hidden on root elements aria#2216
• switch attribute for checkbox inputs #510 => [html-aam PR 510] switch attribute for checkbox inputs aria#2217
• contextual role concept proposal #484 => [html-aam PR 484] contextual role concept proposal aria#2218
• add/revise popover related attribute mappings #481 => [html-aam PR 481] add/revise popover related attribute mappings  aria#2219
• Define concept of minimum role #454 => [html-aam PR 454] Define concept of minimum role aria#2220
• clarify img mappings #451 => [html-aam PR 451] clarify img mappings aria#2221
• handling fallback content for the meter element #401 => [html-aam PR 401] handling fallback content for the meter element aria#2222
• add validity IDL #395 => [html-aam PR 395] add validity IDL aria#2223
• update / expand input value mappings #396 => TODO (pkra: this one was too messy to move over due to the aam table changes)
• Change figure & figcaption accName computation #359 => [html-aam PR 359] Change figure & figcaption accName computation aria#2224