[WIP] Schema v2

[lmolkova]

Early prototype of the new schema URL story. Built on top of #2307

Try it out with make generate-schema-v2-dev NEXT_SEMCONV_VERSION=1.36.0

What it generates:

schemas/
  /1.36.0-dev
    schema.yaml - fully resolved schema with everything defined in semconv, 3MB
    schema-diff.yaml - changes from prev version (just one for the time being)
  /1.36.0
    schema.yaml
    no schema-diff.yaml here, see below

Not done yet:

• semconv manifest in the root like ./schemas/1.36.0-dev/manifest.yaml
• diff history beyond one version
• misc
  • sort resolved schems

Problems found so far:

• diff data has no stability properties, not possible to generate stable one

• a lot of meaningless null in resolved schema

  having `span_kind: null` on metric is not great

  ```yaml span_kind: null events: [] metric_name: http.server.request.duration instrument: histogram unit: s name: null ```

• I'm not sure if lineage is really important on the resolved schema, do we actually need it checked in?

  Can be pretty big

  ```yaml lineage: provenance: registry_id: main path: /home/weaver/source/cli/spans.yaml attributes: error.type: source_group: registry.error inherited_fields: - brief - examples - note - stability locally_overridden_fields: - requirement_level process.command_args: source_group: registry.process inherited_fields: - brief - examples - note - stability locally_overridden_fields: - requirement_level process.executable.name: source_group: registry.process inherited_fields: - brief - examples - note - stability locally_overridden_fields: - requirement_level process.executable.path: source_group: registry.process inherited_fields: - brief - examples - note - stability locally_overridden_fields: - requirement_level process.exit.code: source_group: registry.process inherited_fields: - brief - examples - note - stability locally_overridden_fields: - requirement_level process.pid: source_group: registry.process inherited_fields: - brief - examples - note - stability locally_overridden_fields: - requirement_level ```

• some problems with toyaml filter in jinja

• some discrepancies in weaver commands

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