tests: SynapseBridge bridging in + gas airdrop

[ChiTimesChi]

Description

Tests for #166. The Foundry part is supposed to fail on push (as branch is based of master) and pass on PR.

Checklist

• New Contracts have been tested:
  • Tests for all bridge functions:
    • mint
    • withdraw
      • into chain gas token
      • into regular token
    • mintAndSwap
      • into chain gas token
      • into regular token
      • correct behavior when swap fails due to:
        • desired output amount not reached
        • timestamp deadline for swap already passed
        • incorrect token indices supplied (require mintAndSwap logic rework)
    • withdrawAndRemove (mainnet only)
      • into any of the stables
      • correct behavior when remove fails due to:
        • desired output amount not reached
        • timestamp deadline for swap already passed
        • incorrect token indices supplied (require withdrawAndRemove logic rework)
  • Gas airdrop tests
    • on chains where gas airdrop is enabled
    • on chains where gas airdrop is disabled: check if it can be enabled
  • Test setups for all chains
  • Validity of bridge upgrade is checked (no storage collisions)
• Lint has been run
• I have checked my code and corrected any misspellings

[coveralls]

Pull Request Test Coverage Report for Build 3054976765

• 0 of 2 (0.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 26.817%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
contracts/bridge/SynapseBridge.sol	0	2	0.0%

Totals
Change from base Build 2534578141:	0.0%
Covered Lines:	664
Relevant Lines:	2290

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💛 - Coveralls

[ChiTimesChi]

Some tests (where mintAndSwap is called with identical indices for "from" and "to" tokens) are left in a pending mode: they are now skipped, but can be reenabled whenever PR for updating mintAndSwap and withdrawAndRemove logic is submitted.