[Test Automation] Rectify callbacks with different signatures for tests

This CL adds base::RectifyCallback<>, which takes two callback signatures
and adapts one to the other by eliminating leading arguments the actual
callback doesn't care about.

For example:
using MyCallback = int(A, B)
RectifyCallback<MyCallback>()
can take a callback with any of the following signatures:
 - int()
 - int(B)
 - int(A, B)

This will be used to simplify how we specify test steps in the new
Kombucha 1.5 test framework, by having methods accept arbitrary
signatures and use RectifyCallback<> under the hood:

  AfterShow(kMyElementID,
            base::BindLambdaForTesting(
                [&](){ EXPECT_EQ(..., ...) }))

Rather than:

  AfterShow(kMyElementID,
            base::BindLambdaForTesting(
                [&](ui::InteractionSequence*,
                    ui::TrackedElement*){
                  EXPECT_EQ(..., ...)
                }))

Bug: 1374319
Change-Id: Iba23af602b56e9e30b97d6fde8a8626ba268b21b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3953118
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Commit-Queue: Dana Fried <dfried@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1061871}