x/tools/gopls: release version v0.14.0

[findleyr]

This issue tracks progress toward releasing gopls@v0.14.0.

(We're aiming to cut this release near the end of October, but are going to start cutting prereleases earlier than usual.)

• merge master into gopls-release-branch.0.14
• update hard-coded version
• update go.mod/go.sum (remove x/tools replace, update x/tools version)
• tag gopls/v0.14.0-pre.1
• update Github milestone
• write release notes
• smoke test features
• tag gopls/v0.14.0

[gopherbot]

Change https://go.dev/cl/530977 mentions this issue: all: update codereview.cfg for gopls-release-branch.0.14

[gopherbot]

Change https://go.dev/cl/531035 mentions this issue: all: merge master (fb7463a) into gopls-release-branch.0.14

[gopherbot]

Change https://go.dev/cl/530437 mentions this issue: gopls: update go.mod for v0.14.0-pre.1

[gopherbot]

Change https://go.dev/cl/533155 mentions this issue: all: merge master (ee20ddf) into gopls-release-branch.0.14

[gopherbot]

Change https://go.dev/cl/533177 mentions this issue: gopls: update go.mod for v0.14.0-pre.1