[CIR][CIRGen] Convert trivial copy constructor and assignment operator calls to memcpy

[Arthur-Chang016]

No description provided.

[Arthur-Chang016]

Reimplement the replacement of trivial copy constructor / assignment to cir.copy in the LoweringPrepare phase.

Key Features:

• Find the FuncOp for the trivial copy and check if it's trivial by checking the AST info
• Replaces them with direct cir.copy operations
• Aggressive safety checks: Validates that constructor calls have no return values and exactly 2 operands (dst and src)
• Leave the placeholder for future std::move (not sure if it will be handled here but looks suitable)

[Arthur-Chang016]

Note that clang/test/CIR/CodeGen/eh.cpp is marked Expectedly Failed since it looks like there's CIR parsing issue.

tmp/test.cir:54:14: error: expected '{' to begin a region
    } catch [#cir.unwind {

[Arthur-Chang016]

link issues / pr
#1616
#1202

[bcardosolopes]

LGTM modulo few nits

[Arthur-Chang016]

Thanks for the review!