Add `Node#loc_is?` for easier test of locations #1230

Job	Run time
Main Gem Specs \| RuboCop: master \| 2.7	2m 5s
Coding Style \| 3.0	32s
Main Gem Specs \| RuboCop: master \| 3.0	1m 43s
Prism	26s
Main Gem Specs \| RuboCop: v1.61.0 \| 3.3	1m 59s
Specs \| 2.7	42s
Specs \| 3.0	26s
Specs \| 3.1	26s
Specs \| 3.2	29s
Specs \| 3.3	26s
Specs \| head	28s
Coverage \| 2.7	43s
Specs "modern" \| 3.0	26s
Specs \| jruby	45s
Specs \| jruby-head	44s
Specs \| truffleruby	1m 1s
Specs \| truffleruby-head	1m 9s
	14m 30s

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