deps: update x/tools and gopls to 64986481

[myitcv]

Also drop scenario_modfile per #946

• internal/lsp: check file kind before showing warning 64986481
• go/packages: support overlays for replaced modules 3c2036f9
• tools, gopls: update Go versions in go.mod files to 1.12 2b477fad
• go/packages: add roots for overlaid packages for all query types 8f9ed77d
• internal/lsp: handle staticcheck in code actions 17fc728d
• internal/lsp/source: fix panic in addFieldItems 2350fe8b
• internal/lsp: handle staticcheck in didChangeConfiguration 97363e29
• report cycle when visiting a grey analyzer 6422fca0
• internal/lsp/cache: fix for default -mod=readonly b43031a3
• gopls/internal/regtest: add a test for new symbols in test variants 7ad463ce
• internal/lsp/protocol: add support for upcoming LSP 3.16 d49a6cb6
• internal/lsp/cache: automatically construct the workspace module d179df38
• internal/lsp/source: fix duplicates in workspaceSymbols 571a2076
• internal/lsp: show a warning message when opening an "orphaned" file 53e29e9d
• gopls/internal/regtest: skip failing test for go1.13 and below d6107fe4
• x/gools/gopls: document settings for working on source distribution b484961f
• internal/lsp, go/packages: fix Go 1.15-related overlay bug 44a29229
• gopls/doc: generate settings JSON, docs 6a8222ee
• internal/lsp: add more tests for package completion 201d438b
• gopls/doc: add information about supported Go versions 12e1bf57
• internal/lsp: break up fillstruct testdata to make it more manageable a4118eb6
• internal/lsp: parse Go files through the new snapshot's cache in clone 2e7746ed
• gopls/doc: add memory usage info to troubleshooting guide 27b65b42
• internal/lsp: clean up some of the extract function code 77fbfaef
• internal/lsp/cache: don't set an error by default in load 93a3566f

Fixes #946

[leitzler]

LGTM