Template semconv changes in otelhttp

[MrAlias]

The semantic conventions migration strategy implemented for the otelhttp instrumentation needs to be applied to all other HTTP instrumentation. To do this, the internal/semconv package from needs to be templatized and added to the shared package so other HTTP instrumentation libraries can use it.

• Server semconv template
• Client semconv template

Blocked on otelhttp having a valid implementation:

• Generate New Client Metrics in otelhttp #6261
• Generate New Server Metrics in otelhttp #6262

[MrAlias]

Client semconv template work is still blocked: #5773

[dennisme]

#5773 is merged. Looks like this one is no longer blocked.

[MrAlias]

We still need resolution for #6261 and #6262 to have a complete reference implementation to templatize.