Incompatible target skipping behaves unintuitively for "paths" on the command line

This is a dedicated ticket for an issue mentioned in #12948.

With this root BUILD file:
```python
sh_test(
name = "bar",
srcs = ["BUILD"],
target_compatible_with = ["@platforms//:incompatible"],
)

genquery(
name = "query",
testonly = True,
expression = "//:bar",
scope = ["//:bar"],
)
```
If you run bazel build //:query you get this failure:
```console
% bazel build //:query
ERROR: Target //:query is incompatible and cannot be built, but was explicitly requested.
Dependency chain:
//:query
//:bar <-- target platform didn't satisfy constraint //:incompatible
INFO: Elapsed time: 0.075s
INFO: 0 processes.
FAILED: Build did NOT complete successfully (1 packages loaded, 5 targets configured)
```
If you omit the //: from the target, it skips the genquery all together:
```console
% bazel build query
INFO: Analyzed target //:query (0 packages loaded, 0 targets configured).
INFO: Found 1 target...
Target //:query was skipped
INFO: Elapsed time: 0.100s, Critical Path: 0.00s
INFO: 1 process: 1 internal.
INFO: Build completed successfully, 1 total action
```

As per @gregestren , the `query` is indeed treated as an implicit target. More accurately, it's a [`PATH_AS_TARGET`](https://github.com/bazelbuild/bazel/blob/97bc48d455048cfe873da429ac83aec6c0d347a1/src/main/java/com/google/devtools/build/lib/cmdline/TargetPattern.java#L1106) instead of a `SINGLE_TARGET`. That means the following logic doesn't get triggered:
https://github.com/bazelbuild/bazel/blob/97bc48d455048cfe873da429ac83aec6c0d347a1/src/main/java/com/google/devtools/build/lib/buildtool/AnalysisPhaseRunner.java#L342-L344

I think it would be reasonable for `bazel build query` to produce the same error about incompatbility.

Reproduce the two commands using the root BUILD file shown in the issue, then read TargetPattern.java around PATH_AS_TARGET and AnalysisPhaseRunner.java around lines 342-344. Trace how command-line paths are classified and how incompatible explicitly requested targets are handled; done means bazel build query reports the same incompatibility error as bazel build //:query.

Written by the indexing model from the issue text.