- Fix a bug in the logic to suppress a context cancellation error
  computing the shared import graph.
- Remove ErrIsDefinition. It was introduced for testing in CL 196560,
  and is no longer needed.
- Update golang.SignatureHelp to return (nil, nil) in the case where
  SignatureHelp is simply not available.
- Suppress the mod tidy diagnostic error when GOPROXY=off. It is too
  noisy, and golang/go#56395 tracks the fix for the root cause.
- Suppress noisy errors about semantic tokens. Researching the history
  behind this error, it seems it was only added to force the
  invalidation of semantic tokens client-side. The same can be achieved
  by returning a non-nil, empty result.
- Enforce that marker tests encounter no error logs, with an -errors_ok
  flag to allow them in select cases.
- Update the -min_go version of some marker tests that use a go.mod file
  with a too-new go version. This was an error log.

For golang/go#66746

Change-Id: I21fe274e320cf5fa7d6b85d7402330fb647dbd29
Reviewed-on: https://go-review.googlesource.com/c/tools/+/577655
Reviewed-by: Alan Donovan <adonovan@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

Previously, gopls would log package contents whenever reloading (but not
reinitializing) a workspace--essentially whenever the query did not
contain a '...'. But following a big invalidation, gopls may reload
hundreds or even thousands of packages. Logging them is tremendously
verbose.

Change the behavior to simply log packages if and only if verboseOutput
is set. This is easier to understand and greatly reduces the noisiness
of loading.

Also annotate the one test that broke when I experimented with this
behavior. We should really have a more robust framework for asserting on
loads, but that is a project for another CL.

For golang/go#66746

Change-Id: I0eff7fad1b2deb2f170a1c336abf2c2a9e4f56ba
Reviewed-on: https://go-review.googlesource.com/c/tools/+/577875
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Alan Donovan <adonovan@google.com>

As part of the log audit in golang/go#66746, I noticed several
irregularities addressed by this CL:
- Move "tags" (domain-specific event keys, which are used construct
  labels) closer to the packages that use them. Specifically, the
  internal/event/tag package contained gopls-specific tags, but x/tools
  should not care about gopls.
- Use consistent values for log attributes. For example, "method" was
  being used to mean jsonrpc2 method and Go method. Also, "directory"
  was being used as both file path and URI.
- Use log attributes for the view attributes logged when views are
  created.
- Eliminate (yet another) redundant log during Load.
- Include the ViewID with snapshot.Labels, since snapshot IDs are only
  meaningful relative to a View.

With these changes, my audit of logging is complete.

Fixes golang/go#66746

Change-Id: Iaa60797a7412fb8e222e78e2e58eff2da9563bbb
Reviewed-on: https://go-review.googlesource.com/c/tools/+/579335
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Alan Donovan <adonovan@google.com>

As part of the log audit in golang/go#66746, I noticed several
irregularities addressed by this CL:
- Move "tags" (domain-specific event keys, which are used construct
  labels) closer to the packages that use them. Specifically, the
  internal/event/tag package contained gopls-specific tags, but x/tools
  should not care about gopls.
- Use consistent values for log attributes. For example, "method" was
  being used to mean jsonrpc2 method and Go method. Also, "directory"
  was being used as both file path and URI.
- Use log attributes for the view attributes logged when views are
  created.
- Eliminate (yet another) redundant log during Load.
- Include the ViewID with snapshot.Labels, since snapshot IDs are only
  meaningful relative to a View.

With these changes, my audit of logging is complete.

Fixes golang/go#66746

Change-Id: Iaa60797a7412fb8e222e78e2e58eff2da9563bbb
Reviewed-on: https://go-review.googlesource.com/c/tools/+/579335
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Alan Donovan <adonovan@google.com>