Allow for different default search engines based on region

[rebron]

Test plan

See brave/brave-core#516

Original Description

(Work on browser-laptop was done with brave/browser-laptop#14713)

Brave should use region detection when considering how to set the default search engine (globally and for private tabs)

For example, if I'd like to default to bing.com for Brazil, this should be possible. Currently, the default search is applied regardless of region

The region detection should happen via Node (ex: looking at the computer settings)

Carrying over from browser-laptop
brave/browser-laptop#14647

[bsclifton]

The default search engines (by country) are set in Chromium here:
src/components/search_engines/template_url_prepopulate_data.cc

The first one in the list is set as the default.

There's an accompanying file which has the specifics for each search engine (URL, suggest URL, favicon URL, etc):
src/components/search_engines/prepopulated_engines.json

[srirambv]

Verification Passed on

Brave	0.55.11 Chromium: 70.0.3538.35 (Official Build) beta (64-bit)
Revision	28dcb499844fa40c28d5f62e337876cb936f79f5-refs/branch-heads/3538@{#678}
OS	Linux

• Verified setting device language to de_DE.UTF-8 or fr_FR.UTF-8 changes default search engine to Qwant
• Verified setting FR/DE language shows the localized version of Yahoo page in search list

Verified passed with

Brave	0.55.11 Chromium: 70.0.3538.35 (Official Build) beta(64-bit)
Revision	28dcb499844fa40c28d5f62e337876cb936f79f5-refs/branch-heads/3538@{#678}
OS	Mac OS X

• Verified all scenarios in test plan

Verification Passed on

Brave	0.55.12 Chromium: 70.0.3538.45 (Official Build) beta (64-bit)
Revision	cbdc32e4334458954e9def214d7e5fa1ca1960eb-refs/branch-heads/3538@{#830}
OS	Windows

• Verified all scenarios in test plan