[FIRRTL] Add DomainKind attribute to WireOp for domain-typed Wires

[MrRoy09]

This PR adds a domainKind (FlatSymbolRefAttr) attribute to WireOp to explicitly track domain type information for domain-typed wires (!firrtl.domain)

Summary of Changes

• Added OptionalAttr<FlatSymbolRefAttr> to WireOp arguments in FIRRTLDeclarations.td
• Updated all 4 OpBuilder overloads to accept an optional domainKind parameter with default value FlatSymbolRefAttr()
• Updated getDomainTypeName() to check WireOp::getDomainKindAttr() for domain-typed wires in FIRRTLOps.cpp
• Simplified getDomain() to directly query WireOp::getDomainKindAttr() instead of iteratively following connections in LowerLayers.cpp
• Added testcases to verify domain.define works as expected
• Modifed testcases to include {domainKind = @ClockDomain} on domain-typed wires

Related to #9398