Embed assets in elf file (#2466)

* FBT: file_assets generator
* Elf file: process manifest section externally
* FBT, file_assets generator: add assets signature
* Storage: assets path alias
* Flipper application: assets unpacker
* Apps, Storage: use '/data' alias for apps data
* Storage: copy file to file
* Assets: log flag, fixes
* Update f18 api
* Assets: asserts
* Assets: fix signature_data check
* App assets: example
* Example assets: fix folder structure in readme
* Assets: fix error handling
* Assets builder: use ansii instead of utf-8, use .fapassets section instead of .fapfiles, add assets path to signature
* Elf file: comment strange places
* Storage: totaly optimized storage_file_copy_to_file

applications/examples/example_apps_assets/files/poems/a jelly-fish.txt

@@ -0,0 +1,24 @@
+A Jelly-Fish by Marianne Moore
+
+Visible, invisible,
+A fluctuating charm,
+An amber-colored amethyst
+Inhabits it; your arm
+Approaches, and
+It opens and
+It closes;
+You have meant
+To catch it,
+And it shrivels;
+You abandon
+Your intent—
+It opens, and it
+Closes and you
+Reach for it—
+The blue
+Surrounding it
+Grows cloudy, and
+It floats away
+From you.
+
+source: "https://poets.org/anthology/poems-your-poetry-project-public-domain"