Avoid eager error allocation when parsing named tuples

[Altren]

Allocate error-vector storage only when parsing encounters an error, in both regular and default-value parsing.

Add Point2d vector read benchmarks to the all-format target and CI summaries. Cover 1,000 and 1,000,000 points in JSON, Cereal, MessagePack, and YAS, with serialized size and applicable default-value and positional parsing variants.

Validated all 20 new benchmark cases and the existing JSON tests; local before/after runs show lower read times with unchanged serialized sizes.

For one million Point2d records, the read speedups on my M4 mac were:
1.38x Cereal
1.65x YAS
1.44x MessagePack (with NoFieldNames)

[Altren]

FYI. I'm trying to make reflect-cpp work as fast as native Cereal serialization does, in my production case it is 2x slower for write and 3x slower for read.
And some can be improved for all formats, like this change. I'll create at least one more PR soon

[liuzicheng1987]

@Altren, great.

Thank for this. I am merging.