lsp-erlang: Add initial support for erlang-language-platform #4653

Job	Run time
test (ubuntu-latest, 26.3, false)	2m 52s
test (ubuntu-latest, 27.2, false)	2m 43s
test (ubuntu-latest, 28.2, false)	3m 59s
test (ubuntu-latest, 29.1, false)	3m 23s
test (macos-latest, 26.3, false)	4m 48s
test (macos-latest, 27.2, false)	4m 44s
test (macos-latest, 28.2, false)	6m 14s
test (macos-latest, 29.1, false)	7m 26s
test (windows-latest, 26.3, false)	3m 57s
test (windows-latest, 27.2, false)	3m 56s
test (windows-latest, 28.2, false)	5m 21s
test (windows-latest, 29.1, false)	4m 16s
test (ubuntu-latest, snapshot, true)	2m 45s
test (macos-latest, snapshot, true)	4m 53s
test (windows-latest, snapshot, true)	35s
	1h 1m 52s

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