Sessions shortcode doesn't have order=asc

[andywashere]

The [sessions] shortcode currently does not allow you to sort with an ascending order. Even if you add order=asc, the sessions are still listed in descending order. This means that if you choose orderby=title, sessions are always display in reverse-alphabetical order.

[ryelle]

meta-547.diff​ Add 'order' as a shortcode attribute, default to 'desc'.

[iandunn]

In 799:

WordCamp Post Types: Add order attribute to sessions shortcode.

Fixes #547
props ryelle

[iandunn]

Thanks Kelly :)

Fixes #547

I've decided to use absolute positioning so that the H2 can still be present in the markup. No visual changes.

### Testing

The ToC block is used on Documentation and Developer Resources. Using one of those local environments, or sandbox, switch mu-plugins to this branch.

1. Open pages using the ToC, eg. ​Code Reference, ​Block Editor or ​Optimization
2. On screens < 1200px wide with the ToC inline, the toggle button should fill the header.
3. Expand and contract the ToC
4. Check for regressions on large screens

Followed the testing steps and it worked for me 👍