Use nbgl shared functions

[nroggeman-ledger]

Description

The goal of this PR is to reduce the size in Flash (and RAM) of Applications, by sharing all low-level functions of NBGL with the OS:

• Object management
• Touchscreen management
• Screens management

The architecture/Design document can be found in https://ledgerhq.atlassian.net/wiki/spaces/FW/pages/4750966807/BOLOS+Apps+-+Arch+-+NBGL+sharing+between+FW+and+Apps

Changes include

• Bugfix (non-breaking change that solves an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (change that is not backwards-compatible and/or changes current functionality)
• Tests
• Documentation
• Other (for changes that might not fit in any category)

Breaking changes

For apps non using standard makefiles, there may be some risks if NBGL low-level files are compiled.
Speculos won't work. Use API LEVEL 22

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 9.09091% with 10 lines in your changes missing coverage. Please review.

Project coverage is 35.49%. Comparing base (cb5cfae) to head (621b9be).

Files with missing lines	Patch %	Lines
lib_nbgl/src/nbgl_obj.c	10.00%	9 Missing ⚠️
lib_nbgl/src/nbgl_screen.c	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #768      +/-   ##
==========================================
- Coverage   35.76%   35.49%   -0.28%     
==========================================
  Files          13       13              
  Lines        1591     1606      +15     
==========================================
+ Hits          569      570       +1     
- Misses       1022     1036      +14     

Flag	Coverage Δ
unittests	35.49% <9.09%> (-0.28%)	⬇️

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[yrichard-ledger]

Why do we need to have separate contexts for ux and apps ?

[nroggeman-ledger]

As explained in the architecture document, UX and App are now sharing many variables, but for the communication between App and UX (event forwarding and ability to use events in App), it's sometime necessary to know the number of screens consumed by UX, or, for Touch management, to have separated contexts, to compute NBGL Touch Events (touch duration for example)