Create a separate interface for module guard

[akshay-ap]

Fixes #755

Summary of changes:

• The PR creates a separate interface for Module guards instead of having a single Guard interface for both module transactions and Safe transactions.

• The new Module guard interface i.e, IModuleGuard has two functions:

1. checkModuleTransaction
2. checkAfterExecution

• The updated addresses in migration contracts are taken from logs from the tests.

• Rename interface Guard to ITransactionGuard.

• Fix typo: Rename ModuleTransasctionDetails to ModuleTransactionDetails

Codesize:
Main branch:

Safe 21210 bytes (limit is 24576)
SafeL2 22052 bytes (limit is 24576)

This PR (+571 bytes):

Safe 21781 bytes (limit is 24576)
SafeL2 22623 bytes (limit is 24576)

Changes in PR:

• Documentation
• Fix test cases
• Rebase branch
• Migration contracts

Open for discussion:

1. Rename Guard to ITransactionGuard? -> Yes
2. Rename setGuard function to setTransactionGuard? : Impacts Safe interface
3. Rename ChangedGuard event to ChangedTransactionGuard? Impacts services monitoring this event

[coveralls]

Pull Request Test Coverage Report for Build 9223136085

Details

• 13 of 18 (72.22%) changed or added relevant lines in 6 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-1.5%) to 92.899%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
contracts/base/GuardManager.sol	1	2	50.0%
contracts/examples/guards/DebugTransactionGuard.sol	0	1	0.0%
contracts/examples/guards/ReentrancyTransactionGuard.sol	0	1	0.0%
contracts/base/ModuleManager.sol	9	11	81.82%

Totals
Change from base Build 8900628538:	-1.5%
Covered Lines:	388
Relevant Lines:	400

---

💛 - Coveralls

[remedcu]

Some nits.

Subjective: I like TxGuard or TransactionGuard better than just Guard.

[mmv08]

LGTM. I'd still wait for Nick's or Shebin's approval since this is a highly complex and impactful addition.

[nlordell]

Looks great! One minor nit for comment, and more suggestions for the migration.

[akshay-ap]

Thanks for approval! I will merge it this week after a final self-review as this is an important change in the account contract.