storing large file in bulletin

[rosarp]

Adds example according to #77

[rosarp]

@bkontur the modified code is only common.js
The main function of store_chunked_data.js and store_big_data.js are same.
May be we should merge examples adding documentation instead.

[bkontur]

@bkontur the modified code is only common.js The main function of store_chunked_data.js and store_big_data.js are same. May be we should merge examples adding documentation instead.

Let's keep it as it is, but first, let's start to use PAPI here also, we merged PAPI example:

• so first, refactor please authorizeAccount move and reuse this https://github.com/paritytech/polkadot-bulletin-chain/pull/103/files#diff-b933a3c7d064ad46d61d94593dfb9518b605667774d66a91abb67067a775913eR11-R46 to the common.js
• when working, the next step will be to replace:

if (i > 0 && i % MAX_CHUNKS == 0) {
      await waitForNewBlock();
}

with something sophisticated, we will just push transactions/chunks in the loop until it returns some error "Block is full or similar error", then the loop will wait for another block and again continues to push chunks