x/tools/gopls: release version v0.15.3

[findleyr]

This issue tracks progress toward releasing gopls@v0.15.3

• create or update gopls-release-branch.0.15
• update go.mod/go.sum (remove x/tools replace, update x/tools version)
• tag gopls/v0.15.3-pre.1
• update Github milestone
• write release notes
• smoke test features
• tag gopls/v0.15.3

[gopherbot]

Change https://go.dev/cl/577298 mentions this issue: all: add replace directive to help stage the v0.15.3 release

[gopherbot]

Change https://go.dev/cl/577297 mentions this issue: [gopls-release-branch.0.15] internal/imports: fix two "nil pointer in interface" bugs

[gopherbot]

Change https://go.dev/cl/577261 mentions this issue: [gopls-release-branch.0.15] gopls/internal/server: filter diagnostics to "best" views

[gopherbot]

Change https://go.dev/cl/577301 mentions this issue: [gopls-release-branch.0.15] gopls/internal/cache: fix crash in snapshot.Analyze with patch versions

[gopherbot]

Change https://go.dev/cl/577302 mentions this issue: [gopls-release-branch.0.15] internal/check: filter out too-new Go versions for type checking

[gopherbot]

Change https://go.dev/cl/577303 mentions this issue: [gopls-release-branch.0.15] gopls/internal/cache: avoid panic when the primary diagnostic is broken