fix(contracts): add check for valid mailbox and relayer in `TrustedRelayerIsm`

[aroralanuk]

Description

• minor fix: add an isContract check for mailbox and non-zero check for relayer when instantiating TrustedRelayerIsm

Drive-by changes

None

Related issues

• partly fixes https://github.com/chainlight-io/2024-08-hyperlane/issues/14

Backward compatibility

Yes

Testing

Unit

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⚠️ No Changeset found

Latest commit: d495858d1d711317e58fcc49612945a4f58f5be6

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[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 82.36%. Comparing base (25e5d1a) to head (d495858). Report is 102 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4553      +/-   ##
==========================================
+ Coverage   82.33%   82.36%   +0.02%     
==========================================
  Files         100      100              
  Lines        1421     1423       +2     
  Branches      180      182       +2     
==========================================
+ Hits         1170     1172       +2     
  Misses        251      251              

Components	Coverage Δ
core	96.92% <ø> (ø)
hooks	86.66% <ø> (ø)
isms	93.85% <100.00%> (+0.05%)	:arrow_up:
token	93.46% <ø> (ø)
middlewares	86.52% <ø> (ø)

[yorhodes]

always feel like address(0) checks are not needed any more: forum.openzeppelin.com/t/removing-address-0x0-checks-from-openzeppelin-contracts/2222

you can technically set this as any address that you don't own and its considered "misconfigured"

it is quite useful to catch these configuration issues at deploy time even if solidity will include the 0x0.call check at "runtime"