fix: Forbid usage of :root pseudo-class selector

[pmdartus]

Details

• Throw error when using :root selector (fix :root pseudo class breaks the style encapsulation. #145)
• Extract the selector validation logic from selector-transform.ts
• Add test for transformSelector method

Does this PR introduce a breaking change?

• Yes
• No

[salesforce-best-lwc-internal]

Benchmark results

Base commit: 634f01e | Target commit: 82910b6

lwc-engine-benchmark

table-append-1k	metric	base(634f01e)	target(82910b6)	trend
benchmark-table/append/1k	duration	145.50 (± 4.30 ms)	146.40 (± 4.40 ms)	-0.62% 👌

table-clear-1k	metric	base(634f01e)	target(82910b6)	trend
benchmark-table/clear/1k	duration	11.50 (± 0.40 ms)	11.40 (± 0.50 ms)	0.87% 👌

table-create-10k	metric	base(634f01e)	target(82910b6)	trend
benchmark-table/create/10k	duration	848.60 (± 5.20 ms)	839.80 (± 4.80 ms)	1.04% 👍

table-create-1k	metric	base(634f01e)	target(82910b6)	trend
benchmark-table/create/1k	duration	102.10 (± 1.90 ms)	101.30 (± 2.00 ms)	0.78% 👌

table-update-10th-1k	metric	base(634f01e)	target(82910b6)	trend
benchmark-table/update-10th/1k	duration	93.00 (± 3.80 ms)	91.90 (± 5.00 ms)	1.18% 👌

tablecmp-append-1k	metric	base(634f01e)	target(82910b6)	trend
benchmark-table-component/append/1k	duration	251.80 (± 4.20 ms)	243.70 (± 4.70 ms)	3.22% 👍

tablecmp-clear-1k	metric	base(634f01e)	target(82910b6)	trend
benchmark-table/clear/1k	duration	32.80 (± 1.10 ms)	31.50 (± 1.70 ms)	3.96% 👍

tablecmp-create-10k	metric	base(634f01e)	target(82910b6)	trend
benchmark-table-component/create/10k	duration	1689.40 (± 9.60 ms)	1689.80 (± 8.80 ms)	-0.02% 👌

tablecmp-create-1k	metric	base(634f01e)	target(82910b6)	trend
benchmark-table-component/create/1k	duration	192.30 (± 4.30 ms)	190.60 (± 3.20 ms)	0.88% 👍

tablecmp-update-10th-1k	metric	base(634f01e)	target(82910b6)	trend
benchmark-table-component/update-10th/1k	duration	75.40 (± 4.00 ms)	73.70 (± 3.90 ms)	2.25% 👌