tracing: simplify level event macros

The level event macros (e.g. `trace!`, `info!`) call into the `event!`
macro with the level set appropriately. However, these macros have
become complex, covering many different cases and reaching aroudn 250
lines of patterns.

As discovered in #3437, there were many cases where these level event
macros didn't correctly handle patterns which the `event!` macro does
handle.

This change simplifies the event macros to delegate more parsing to the
common `event!` macro patterns. Rather than matching all the possible
field patterns, the level event macros only match the directives (name,
target, and parent or some combination thereof). The remainder of the
macro invocation is matched as a token tree (`tt`) and passed as is to
the `event!` macro.

This reduces the patterns to only the 8 combinations of directives
(including no directives at all), reducing the previous 250 lines of
patterns for each macro down to around 25 lines instead.

Additionally, an unqualified use of `Some` in the `valueset` macro has
been fixed, as this affected all event macros (`event!` and all the
level event macros).

With these changes, the comprehensive checks introduced in #3437 now all
pass and so the job can be fully enabled to fail on CI.

Author: hds

.github/workflows/CI.yml

@@ -325,8 +325,7 @@ jobs:
     - name: "Generate macro tests"
       run: cargo run --bin xtask -- gen-macro-tests
     - name: "Check tracing macro invocations ("
-      # TODO(hds): remove `|| true` when all macros compile
-      run: cargo check --tests || true
+      run: cargo check --tests
       working-directory: "tracing/test-macros"
 
   # all required checks except for the main test run (which we only require