fix: Do not add fake root for searches with context

[mykola-mokhnach]

When page source is built for the whole elements hierarchy that a fake hierarchy root is added, which contains some additional info about the display. It is also used as a holder for toast elements. Although, it makes no sense to add the same stuff to context searches where the xml root is some subelement.

appium/appium#14509

[dpgraham]

Here is an overview of what got changed by this pull request:

Complexity increasing per file
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- app/src/main/java/io/appium/uiautomator2/model/UiElementSnapshot.java  8
         

See the complete overview on Codacy

[mykola-mokhnach]

@sshock I assume this change could also improve the perf of your tests if you use nested lookups

[sshock]

@mykola-mokhnach I don't think we are using any nested lookups, but happy to see more performance improvements and thanks for tagging me!