P/Invoke extern event has unexpected metadata

[jjonescz]

Version Used: 347e576

Steps to Reproduce:

Run the following test:

[Fact]
public void ExternEvent()
{
    var source = """
        using System;
        using System.Runtime.InteropServices;
        public static class C
        {
            [method: DllImport("something.dll")]
            public static extern event EventHandler E;
        }
        """;
    CompileAndVerify(source,
        symbolValidator: verify,
        verify: Verification.Skipped)
        .VerifyDiagnostics();

    static void verify(ModuleSymbol module)
    {
        var ev = module.GlobalNamespace.GetMember<EventSymbol>("C.E");
        Assert.True(ev.GetPublicSymbol().IsExtern);
        verifyAccessor(ev.AddMethod!);
        verifyAccessor(ev.RemoveMethod!);
    }

    static void verifyAccessor(MethodSymbol accessor)
    {
        Assert.True(accessor.GetPublicSymbol().IsExtern);

        var importData = accessor.GetDllImportData()!;
        Assert.Equal("something.dll", importData.ModuleName);
        Assert.Equal(accessor.MetadataName, importData.EntryPointName); // 'add_E' or 'remove_E' expected
    }
}

Or simply compile the following program and inspect the IL:

using System;
using System.Runtime.InteropServices;
public static class C
{
    [method: DllImport("something.dll")]
    public static extern event EventHandler E;
}

Expected Behavior: Both add_E and remove_E accessors to be similar.

Actual Behavior: add_E accessor emitted with pinvokeimpl("something.dll" as "remove_E" winapi):

.class public auto ansi abstract sealed beforefieldinit C
	extends [System.Runtime]System.Object
{
	// Methods
	.method public hidebysig specialname static pinvokeimpl("something.dll" as "remove_E" winapi) 
		void add_E (
			class [System.Runtime]System.EventHandler 'value'
		) cil managed preservesig 
	{
		.custom instance void [System.Runtime]System.Runtime.CompilerServices.CompilerGeneratedAttribute::.ctor() = (
			01 00 00 00
		)
	} // end of method C::add_E

	.method public hidebysig specialname static pinvokeimpl("something.dll" winapi) 
		void remove_E (
			class [System.Runtime]System.EventHandler 'value'
		) cil managed preservesig 
	{
		.custom instance void [System.Runtime]System.Runtime.CompilerServices.CompilerGeneratedAttribute::.ctor() = (
			01 00 00 00
		)
	} // end of method C::remove_E

	// Events
	.event [System.Runtime]System.EventHandler E
	{
		.addon void C::add_E(class [System.Runtime]System.EventHandler)
		.removeon void C::remove_E(class [System.Runtime]System.EventHandler)
	}
} // end of class C