Verbose flag for rewards

[NejcZdovc]

Test Plan

--enable-logging=stderr --v=0 --vmodule=*rewards*=5 - you should see the requests and responses for rewards being dumped into the terminal/CLI

--enable-logging --v=0 --vmodule=*rewards*=5 - you should see the requests and responses for rewards being dumped into /BraveSoftware/Brave-Browser-Beta/chrome_debug.log
On Windows: AppData\Local\BraveSoftware\Brave-Browser-Beta\User Data\chrome_debug.log

Note: You can control the amount of logs you receive using --v=1, --v=2 and --v=3 as @NejcZdovc mentioned below but be warned, there's a LOT of data that's dumped. If you're not using --v=0, I would recommend dumping the log into chrome_debug.log or you'll flood the terminal.

Original Posted Issue

Add option for QA to print out logs into the terminal.

QA will be able to use LOG/VLOG for rewards.

We should have 5 levels:

ERROR = 1,
WARNING = 2,
INFO = 3,
REQUEST = 4,
RESPONSE = 5

You can use 1-3 levels like normal logs npm start -- --v=2, where 2 is level.

For 4-5 we use it as verbose logging.You can use it like npm start -- --vmodule=*rewards*=4, where 4 is level. If you specify 4 as a level, you will get logs for levels 4. If you specify 5, you will get levels 4 and 5.

[kjozwiak]

Went through verification using the following build under macOS 10.14 x64 - PASSED

Brave	0.57.8 Chromium: 71.0.3578.53 (Official Build) beta(64-bit)
Revision	599fb72e740eab9d10609f1ed28a2ad669f82c1a-refs/branch-heads/3578@{#669}
OS	Mac OS X

Verification PASSED on

Brave	0.57.8 Chromium: 71.0.3578.53 (Official Build) beta(64-bit)
Revision	599fb72e740eab9d10609f1ed28a2ad669f82c1a-refs/branch-heads/3578@{#669}
OS	Windows 7

On Windows log path is: AppData\Local\BraveSoftware\Brave-Browser-Beta\User Data\chrome_debug.log

Verification PASSED on Ubuntu 17.10

Brave	0.57.8 Chromium: 71.0.3578.53 (Official Build) beta(64-bit)
Revision	599fb72e740eab9d10609f1ed28a2ad669f82c1a-refs/branch-heads/3578@{#669}
OS	Linux

On Linux log path is: [user].config/BraveSoftware/Brave-Browser-Beta/chrome_debug.log