[RELEASE] Prepare release opentelemetry-cpp 1.19.0

[marcalff]

No release date yet.

Must have:

• [EXPORTER] Support handling retry-able errors for OTLP/HTTP #3223
• [EXPORTER] Support handling retry-able errors for OTLP/gRPC #3219
• [SDK] Better control of threads executed by opentelemetry-cpp #3175

Desirable:

• [SDK] Fix lifetime of GlobalLogHandler #3221
• [Code Health] Include what you use, part 6 #3216
• [Code Health] Include what you use, part 7 #3238
• [SDK] Optimize Metric Processing for Single Collector with Delta Temporality #3236

Postponed to next release:

• Fix lifetime for sdk::ReadWriteLogRecord #3147

[ThomsonTan]

Could we wait for below PR to be included?

#3236

[lalitb]

Could we wait for below PR to be included?

#3236

I will address the review comments today.