Blockchain integrations

refactoring customized names, logos, messages, links, and tokens id based on selected blockchain
added blockchain helpers for texts & descriptors
added blockchain helpers for logos
only show Latest exchange rate for OmniExplorer
renamed Ecosystem menu entry to Blockchain
refactoring LinkPreview based on selected blockchain
improving of Footer with links and meaningful data
hided footer section links for small screens
changed contact link to omniwallet contact in promote section

OmniLayer / omniexplorer