fix: [N03]: Removal of Duplicate computations

[chrismaree]

Motivation

OZ Identified the following issue:

In the ProposerV2 contract, the function resolveProposal performs two subsequent
calls to AdminIdentifierLib._constructIdentifier(id) in line 91 and line 99
without storing the return value.
Consider performing only one call and capturing the return value to enhance the gas efficiency
of your code.

The solution in this PR:
Store the identifier and re-use it to avoid double computation.

Summary

Briefly summarize what changes were made to accomplish the motivation above.

Details

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Testing

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• Ran end-to-end test, running the code as in production
• New unit tests created
• Existing tests adequate, no new tests required
• All existing tests pass
• Untested

Issue(s)

Fixes #XXXX

[mrice32]

LGTM!