ref: Instantiating _tags for Spans lazily

[bitsandfoxes]

Lazy tag creation for spans.

OLD:
|                  Method | SpanCount |        Mean |        Error |     StdDev |     Gen0 |     Gen1 |  Allocated |
|------------------------ |---------- |------------:|-------------:|-----------:|---------:|---------:|-----------:|
| 'Creates a Transaction' |         1 |    19.95 us |     8.426 us |   0.462 us |   2.2278 |   0.8545 |   11.79 KB |
| 'Creates a Transaction' |        10 |    60.71 us |    28.927 us |   1.586 us |   5.6152 |   2.0752 |   32.29 KB |
| 'Creates a Transaction' |       100 |   485.11 us |    24.521 us |   1.344 us |  40.0391 |  13.6719 |  238.07 KB |
| 'Creates a Transaction' |      1000 | 4,790.64 us | 2,046.437 us | 112.172 us | 390.6250 | 140.6250 | 2291.61 KB |

NEW:
|                  Method | SpanCount |        Mean |       Error |     StdDev |     Gen0 |    Gen1 |  Allocated |
|------------------------ |---------- |------------:|------------:|-----------:|---------:|--------:|-----------:|
| 'Creates a Transaction' |         1 |    19.34 us |    12.07 us |   0.662 us |   1.8616 |  0.6714 |   10.98 KB |
| 'Creates a Transaction' |        10 |    56.41 us |    36.59 us |   2.006 us |   4.5166 |  1.4648 |   24.16 KB |
| 'Creates a Transaction' |       100 |   398.66 us |    27.15 us |   1.488 us |  37.5977 |  9.7656 |  156.81 KB |
| 'Creates a Transaction' |      1000 | 3,723.91 us | 3,241.45 us | 177.675 us | 343.7500 | 85.9375 | 1479.07 KB |

#skip-changelog

[bruno-garcia]

dang that was simple, no other calls to Tags that can move to InternalTags?

[bitsandfoxes]

dang that was simple, no other calls to Tags that can move to InternalTags?

Nope. All other instances of Tags are not coming from SpanTracer so we only special case that right now.