Improve autofocus prevention after `[` and `]`

Improve autofocus prevention after `[` and `]`

When you go to the next page of GitHub’s code search results, the page is loaded
with AJAX. GitHub then annoyingly focuses its search input. This autofocus
cannot be prevented in a reliable way, because the case is indistinguishable
from a button whose job is to focus some text input. However, after the `[` and
`]` command we know for sure that we can prevent the next focus. This commit
resets the `vim.state.hasInteraction` flag in those commands to allow for this
behavior, by adding the `value=true` parameter to `vim.markPageInteraction()`
and passing in `false`.

Fixes #675.