Introduce Trade section under feature flag

[vytick]

We want to start developing Trade and want start to add it to the app. To do that we want to introduce featureflag and add new stack+ empty screen to tab bar.

• add new feature flag to featureFlagsSlice and set default value to false and add ui to module-dev-utils like for other ff
• add new stack in package module-trading for trade feature with new empty screen that will be initial screen for this
• add new icon for that tab based on the docs
• add this to tab bar according to the design

Expected outcome:

• Unless featureflag is enabled, there is no Trade tab
• ff can be enabled in Dev utils
• Trade tab is present once ff is enabled
• On selecting the tab, there is new empty screen

[vytick]

@trezor/qa Please add to sanity tests, that Trade tab is not visible on iOS or on Android in release build.

[STew790]

QA OK

• added that trade tab should be hidden behind ff to sanity tests
• trade tab is visible after enabling ff in the bottom bar
• trade tab has an "empty" placeholder screen:

Info
25.1.3 3a8d2da