fix: Escape backtick and backslash in CSS

[pmdartus]

Details

Escape backtick and backslash in CSS source. In any CSS file, today usage of:

• backtick makes the compiler produce an invalid javascript
• backslash escape the next character

Fix #530

Does this PR introduce a breaking change?

• Yes
• No

[salesforce-best-lwc-internal]

Benchmark results

Base commit: 84fbfd0 | Target commit: de48a89

lwc-engine-benchmark

table-append-1k	metric	base(84fbfd0)	target(de48a89)	trend
benchmark-table/append/1k	duration	149.00 (± 3.90 ms)	145.90 (± 3.80 ms)	2.08% 👍

table-clear-1k	metric	base(84fbfd0)	target(de48a89)	trend
benchmark-table/clear/1k	duration	12.00 (± 0.70 ms)	12.10 (± 0.60 ms)	-0.83% 👌

table-create-10k	metric	base(84fbfd0)	target(de48a89)	trend
benchmark-table/create/10k	duration	849.30 (± 4.80 ms)	844.20 (± 6.10 ms)	0.60% 👍

table-create-1k	metric	base(84fbfd0)	target(de48a89)	trend
benchmark-table/create/1k	duration	100.80 (± 2.20 ms)	101.80 (± 1.70 ms)	-0.99% 👌

table-update-10th-1k	metric	base(84fbfd0)	target(de48a89)	trend
benchmark-table/update-10th/1k	duration	83.40 (± 2.60 ms)	85.40 (± 5.80 ms)	-2.40% 👌

tablecmp-append-1k	metric	base(84fbfd0)	target(de48a89)	trend
benchmark-table-component/append/1k	duration	224.45 (± 6.80 ms)	226.90 (± 4.80 ms)	-1.09% 👌

tablecmp-clear-1k	metric	base(84fbfd0)	target(de48a89)	trend
benchmark-table-component/clear/1k	duration	36.20 (± 1.80 ms)	36.10 (± 2.20 ms)	0.28% 👌

tablecmp-create-10k	metric	base(84fbfd0)	target(de48a89)	trend
benchmark-table-component/create/10k	duration	1558.20 (± 8.60 ms)	1518.10 (± 10.60 ms)	2.57% 👍

tablecmp-create-1k	metric	base(84fbfd0)	target(de48a89)	trend
benchmark-table-component/create/1k	duration	169.10 (± 3.70 ms)	169.70 (± 3.40 ms)	-0.35% 👌

tablecmp-update-10th-1k	metric	base(84fbfd0)	target(de48a89)	trend
benchmark-table-component/update-10th/1k	duration	79.00 (± 4.30 ms)	78.10 (± 4.30 ms)	1.14% 👌

wc-append-1k	metric	base(84fbfd0)	target(de48a89)	trend
benchmark-table-wc/append/1k	duration	265.60 (± 10.20 ms)	257.90 (± 17.10 ms)	2.90% 👌

wc-clear-1k	metric	base(84fbfd0)	target(de48a89)	trend
benchmark-table-wc/clear/1k	duration	36.30 (± 1.20 ms)	36.20 (± 1.10 ms)	0.28% 👌

wc-create-10k	metric	base(84fbfd0)	target(de48a89)	trend
benchmark-table-wc/create/10k	duration	1978.40 (± 6.60 ms)	1978.00 (± 8.60 ms)	0.02% 👌

wc-create-1k	metric	base(84fbfd0)	target(de48a89)	trend
benchmark-table-wc/create/1k	duration	209.90 (± 4.70 ms)	213.70 (± 4.10 ms)	-1.81% 👎

wc-update-10th-1k	metric	base(84fbfd0)	target(de48a89)	trend
benchmark-table-wc/update-10th/1k	duration	75.50 (± 4.10 ms)	76.20 (± 5.30 ms)	-0.93% 👌

[caridy]

I'm ok with this. I actually think that we can probably freeze the new style function that you're creating in another PR so it can't be tampered with.