Add Histogram Macros to Skia

Adds a set of histogram macros to Skia, modeled after Chrome's
UMA_HISTOGRAM_* macros. These allow logging of high frequency events,
and are useful to analyze real world usage of certain features.

By default, these macros are no-ops. Users can provide a custom
header file which defines these macros if they wish to collect
histogram data. Chrome will provide such a header.

I've currently only added two macros:
- SK_HISTOGRAM_BOOLEAN - logs a true/false type relationship (whether
we are tiling a texture or not on each draw).
- SK_HISTOGRAM_ENUMERATION - logs a set of potential values (which of
a number of choices were selected for the texture upload path).

We could add more unused macros at the moment, but it seems easier to
add these as needed, WDYT?

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1652053004

Review URL: https://codereview.chromium.org/1652053004

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