docs(input, searchbar, textarea): improve docs for managing focus

[mapsandapps]

Issue number: Related to #18132

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What is the current behavior?

The documentation about the autofocus prop is unclear and does not accurately reflect how it actually works across browsers and devices.

What is the new behavior?

• The documentation for autofocus and setFocus are more detailed.
• The documentation links to the relevant page in the docs.

Does this introduce a breaking change?

• Yes
• No

Other information