feat(toolbar): support dynamic type

[liamdebeasi]

Issue number: N/A

---

What is the current behavior?

Most of the work to support dynamic type has been handled in individual components such as ion-title, ion-button, and ion-back-button. However, I noticed two issues:

1. Searchbars in toolbars do not scale with dynamic type.
2. Toolbar has code that targets an improper usage of ion-back-button. The following code set the height of the ion-back-button when used in a toolbar with a searchbar:

   ionic-framework/core/src/components/toolbar/toolbar.ios.scss

   Lines 51 to 53 in 01fc9b4

   	:host(.toolbar-searchbar) ::slotted(ion-back-button) {
   	height: 38px;
   	}

However, this code should never apply because ion-back-button should be slotted inside of ion-buttons not ion-back-button. Slotting ion-back-button directly inside of ion-toolbar causes the back button and searchbar to appear on different lines.

What is the new behavior?

• Updated searchbar to scale in a toolbar
• Added test for new searchbar behavior
• Removed code targeting improper usage

Does this introduce a breaking change?

• Yes
• No

Other information

[bolt-new-by-stackblitz]

Run & review this pull request in StackBlitz Codeflow.

[mapsandapps]

It took me a while to figure out that none of the weird things I'm seeing with toolbars are actually related to the toolbar styles. It looks like this PR has all that's needed for the toolbar itself 👍🏻