Support ParaTimes deposit/withdraw (oasisscan only)

[lukaw3d]

The initial versions should be hidden behind a flag or dev-only, until all warnings are reimplemented.

[lukaw3d]

Some issues:

• no support in oasismonitor
• no support for ledger accounts
• needs to model more oasisscan endpoints in swagger
• needs to show list of paratime transactions
• needs import of ethereum-compatible private keys

[lukaw3d]

Current extension has fee amount and fee gas hardcoded:

• https://github.com/oasisprotocol/oasis-wallet-ext/blob/ccaf2b841888cd7187c89ab0e812b635f62efe64/src/popup/pages/Send/index.js#L187-L189
• https://github.com/oasisprotocol/oasis-wallet-ext/blob/542bb4b0f6fa6928027378681819e61bdee3a054/src/background/api/txHelper.js#L312

It would be better to query RPC queryMinGasPrice. For reference, @pro-wh abandoned it because of complexity:

• https://github.com/oasisprotocol/oasis-wallet-ext/pull/230/files#diff-e9bce3b0c0aee8d5bc193829767cd3b862c8c7431c55435133c9c80c5e1b2ff1R236

[lukaw3d]

Related: warnings in extension

• Add warnings before paratime transactions oasis-wallet-ext#236
• Fix warning when depositing to cipher paratime to default address oasis-wallet-ext#245
• Block confirming dangerous actions oasis-wallet-ext#271

[lukaw3d]

Related PRs so far:
#856
#859
#962
#969
#978
#988
#992
#1114
#1326
#1327
#1346
#1347
#1352
#1353
#1365
#1386

[lukaw3d]

Snippet for gas estimation:
oasisprotocol/oasis-wallet-ext#320 (comment)