feat: add Attributes APIs

[Flash0ver]

Description

Attributes are searchable Name-Value-Pairs with a Type and an optional Unit

• where currently supported Types for the Values are
  • string and string[]
  • boolean and boolean[]
  • integer and integer[] (64-bit signed integral number)
  • double and double[] (64-bit floating-point number)
• where the optional Units must be supported by Relay
  • may be removed or set to none otherwise

Precedence of Attributes on Logs and Metrics - higher priorities overwrite lower priorities:

1. Default Attributes
2. Scope Attributes
3. SDK-APIs
   • Attributes passed via SentrySdk.Logger.Log{SentryLogLevel} methods
   • Attributes passed via SentrySdk.Experimental.Metrics.Emit{SentryMetricType} methods
4. Option-APIs
   • Attributes set via SentryOptions.SetBeforeSendLog(Func<SentryLog, SentryLog?>)
   • Attributes set via SentryOptions.SetBeforeSendMetric<T>(Func<SentryMetric<T>, SentryMetric<T>?>)

Add Attributes APIs for

• Logs
• Metrics
• Scopes

See related docs

• Logs: https://develop.sentry.dev/sdk/telemetry/logs/
• Metrics: https://develop.sentry.dev/sdk/telemetry/metrics/
• Scopes: https://develop.sentry.dev/sdk/telemetry/scopes/
• Attributes: https://develop.sentry.dev/sdk/telemetry/attributes/

In the longer term, this (may) act as a replacement / unification of Tags and Extras.

[linear]

NET-573

[Flash0ver]

Naming hint: see #4834 (comment)

[Flash0ver]

While at it, we may want to remove the Enricher, and instead push the information onto the "Root-Scope" at init-time, which is then applied to Events and such. The Scope might have various internal (extension) methods ("base" ApplyTo, "ApplyToFeedback", ...).
Another layer of complexity we could simplify is the IEventLike-hierarchy of interfaces.
Thanks @bitsandfoxes for the input ... I'll come back to that once we "Scope-ify" our infrastructure.

[jamescrosswell]

While at it, we may want to remove the Enricher, and instead push the information onto the "Root-Scope" at init-time

@Flash0ver this might help with that (introduces a way to init properties on the root scope)...

• feat: User.Id can now be overriden (set to null) in Global mode #5039 (comment)