[logging] Centralize configuration for trace flags

[drfloob]

All TraceFlags are now configured in src/core/lib/debug/trace_flags.yaml. The format is:

my_flag:
  default: false                   # the default value; default=false
  description: Some Description
  debug_only: false                # debug_only flags only work in debug builds; default=false
  internal: false                  # internal flags will not show up in documentation; default=false

To regenerate the trace flag source code, run tools/codegen/core/gen_trace_flags.py (requires mako). This script is also run when sanity checking.

This PR also adds two new features:

Glob-based flag configuration

Trace flag configuration now supports ? (single wildcard character) and * (one or more wildcard characters). For example, using GRPC_TRACE='event_engine*' will enable all flags that match that glob. It expands to:

• event_engine
• event_engine_client_channel_resolver
• event_engine_dns
• event_engine_endpoint
• event_engine_endpoint_data
• event_engine_poller

A cleaner trace-logging macro in abseil logging format

If your goal is only to add log statements when the fault_injection_filter trace flag is enabled, you can use the macro:

GRPC_TRACE_LOG(fault_injection, INFO) << "Filtered:" << 42;

When the trace flag is enabled, the the log will show something like this:

I0000 00:00:1715733657.430042      16 file.cc:174] Filtered:42

---

Note: just like with the gpr_log to abseil logging conversion, the pre-existing trace logging usages can be replaced with the new tracing macro across multiple PRs.

[drfloob]

Pretty close now!

[markdroth]

This looks fantastic!

[tanvi-jagtap]

@drfloob : Please can you let me know approximately when this PR will be submitted. I will avoid editing the files in the PR for some time to avoid more merge conflicts for both of us.
In the meantime I can finish all other files that need gpr to absl migration.

[ctiller]

I'd prefer (where & flag) != 0 here, for the same reasons we usually write != nullptr for pointers -- this is an int not a bool.

[markdroth]

+1 -- but don't need the parens.

[drfloob]

Fixed. It does require parens though, != has higher precedence than &. http://go/cppref/cpp/language/operator_precedence

[drfloob]

@drfloob : Please can you let me know approximately when this PR will be submitted. I will avoid editing the files in the PR for some time to avoid more merge conflicts for both of us. In the meantime I can finish all other files that need gpr to absl migration.

@tanvi-jagtap Thanks. I'll try to wrap it up this week, I have a bit of codegen work to do.