Merge #79: Embed monospaced font

67f26319a0 gui: Add monospaced font settings (Hennadii Stepanov)
22e0114d05 qt: Choose monospaced font in C++ code rather in `*.ui` file (Hennadii Stepanov)
623de12d04 qt: Make GUIUtil::fixedPitchFont aware of embedded font (Hennadii Stepanov)
89e421918e gui: Add Roboto Mono font (Hennadii Stepanov)

Pull request description:

  Qt does not guarantee that the actual applied font matches to the requested one.
  It was noted (https://github.com/bitcoin/bitcoin/pull/16432#issuecomment-514486077):
  > the monospace font looks a bit weird no macOS

  ... because it is _not_ monospaced.
  Also some discrepancies I've noted on Windows while testing Qt 5.15 ([#19716](https://github.com/bitcoin/bitcoin/pull/19716)).

  Of course, we could check the actual font with `QFontInfo`, and try to choose another font.
  But this PR suggests to just embed a monospaced font, and get the GUI look (partially) independent from a platform.

  [Roboto Mono](https://fonts.google.com/specimen/Roboto+Mono) was chosen after discussion with Bitcoin Design community, and due to its [Apache License, Version 2.0](https://fonts.google.com/specimen/Roboto+Mono#license).

  Changes are scoped to the Overview page only.

  ---

  Screenshots on macOS 10.15.6 (images are simulated by code patching):

  - master (ca30d34cf9)
  ![Screenshot from 2020-09-03 14-10-03](https://user-images.githubusercontent.com/32963518/92107902-30357d80-edef-11ea-8a4f-b4c758eebf66.png)

  - this PR (3fdd5b6bd17a679d6e3876682266092159c52d59)
  ![Screenshot from 2020-09-03 15-41-36](https://user-images.githubusercontent.com/32963518/92116277-4b5aba00-edfc-11ea-8cb9-22fc44460bfb.png)

  ---

  More screenshots added after https://github.com/bitcoin-core/gui/pull/79#issuecomment-782909149:

  - Linux Mint 20.1 + Cinnamon DE

  ![DeepinScreenshot_select-area_20210221205410](https://user-images.githubusercontent.com/32963518/108635739-b327be80-7489-11eb-8851-ac89f61199ee.png)

  - Windows 10 (with depends)

  ![DeepinScreenshot_select-area_20210221205056](https://user-images.githubusercontent.com/32963518/108635741-b6bb4580-7489-11eb-8b6b-66be5551eb8c.png)

  - macOS Big Sur (with depends)

  ![DeepinScreenshot_select-area_20210221202917](https://user-images.githubusercontent.com/32963518/108635746-bd49bd00-7489-11eb-8cd2-cf4bb2273a6d.png)

ACKs for top commit:
  laanwj:
    Tested ACK 67f26319a0

Tree-SHA512: a59775570b8ce314669ede50a0b69f53e8a47a41e7eea428835013240f0ce9afcff6e4c258895455b56806417ed877e5b7a9522f1904e95a5f435db8ccf6078c

contrib/debian/copyright

@@ -87,6 +87,10 @@ Files: src/qt/res/icons/proxy.png
 Copyright: Cristian Mircea Messel
 License: public-domain
 
+Files: src/qt/fonts/RobotoMono-Bold.ttf
+License: Apache-2.0
+Comment: Site: https://fonts.google.com/specimen/Roboto+Mono
+
 
 License: Expat
  Permission is hereby granted, free of charge, to any person obtaining a
@@ -144,3 +148,14 @@ Comment:
 
 License: public-domain
  This work is in the public domain.
+
+License: Apache-2.0
+ Licensed under the Apache License, Version 2.0 (the "License");
+ you may not use this file except in compliance with the License.
+ You may obtain a copy of the License at
+ http://www.apache.org/licenses/LICENSE-2.0
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.