Replace with rbs-inline style type definition in lexer directory #1502

Job	Run time
check-misc (head)	12s
steep-check (head)	18s
test-memory (head)	31s
test-ruby (head, master)	6m 16s
test-ruby (3.0, master)	6m 17s
test-windows (head)	1m 50s
ruby-versions / Generate Ruby versions	3s
test-cpp (head, g++)	12s
test-c (head, cc)	15s
test (2.5)	28s
test-cpp (head, clang++)	19s
test-c (head, gcc)	14s
test (2.6)	30s
test-c (head, clang)	22s
test (2.7)	24s
test (3.0)	20s
test (3.1)	25s
test (3.2)	16s
test (3.3)	14s
test (3.4)	21s
test (head)	11s
	19m 58s

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