WIP - [remote] Allow longpress mod for remote keymaps

[phunkyfish]

Description

The longpress mod does not work for remote keymaps (only keyboard keymaps).

This PR is an attempt at adding this to remote keymaps. Need to get it into a librelec build so I can test.

If I hold the ok button I get many of these:

2019-10-08 15:29:38.477 T:742   DEBUG: PushCecKeypress - received key  b duration 0
2019-10-08 15:29:38.509 T:707   DEBUG: HandleKey: 11 (0x0b, obc244) pressed, action is Select

Followed by:

2019-10-08 15:29:44.514 T:742   DEBUG: PushCecKeypress - received key  b duration 0
2019-10-08 15:29:44.521 T:707   DEBUG: HandleKey: 11 (0x0b, obc244) pressed, action is Select
2019-10-08 15:29:44.620 T:742   DEBUG: PushCecKeypress - received key  b duration 1326

Keypresses are logged from: peripherals/devices/PeripheralCecAdapter.cpp

Motivation and Context

New PVR Guide nav controls are not accessible to CEC users that can only use remote keymaps. In addition this would be really useful for low button remotes.

How Has This Been Tested?

Screenshots (if appropriate):

Types of change

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] Clean up (non-breaking change which removes non-working, unmaintained functionality)
• [X] Improvement (non-breaking change which improves existing functionality)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that will cause existing functionality to change)
• [ ] Cosmetic change (non-breaking change that doesn't touch code)
• [ ] None of the above (please explain below)

Checklist:

• [X] My code follows the Code Guidelines of this project
• [ ] My change requires a change to the documentation, either Doxygen or wiki
• [ ] I have updated the documentation accordingly
• [X] I have read the Contributing document
• [ ] I have added tests to cover my change
• [ ] All new and existing tests passed