use embed for embeding assets

[ilgooz]

Go 1.16 will be released soon with embed.

Switch to embed for all assets (dev ui, protobufjs, cosmosfaucet's swagger, lp/sg templates).

[ilgooz]

lp/sg templates and protobufjs (by nodetime) embedded with Go's embed in different PRs. others refactored with the PRs that linked to this issue.