Format svg tags in the same way html tags are formatted

[Artur-]

Description

lit-html uses svg template tag for rendering svgs or embedding svgs inside html. This change enables prettier to format the contents of the svg tag.

Checklist

• I’ve added tests to confirm my change works.
• (If changing the API or CLI) I’ve documented the changes I’ve made (in the docs/ directory).
• (If the change is user-facing) I’ve added my changes to changelog_unreleased/*/XXXX.md file following changelog_unreleased/TEMPLATE.md.
• I’ve read the contributing guidelines.

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[thorn0]

Unfortunately, changes like this are currently blocked by #5588. Until a solution for that is found and implemented, we can't move forward with adding more embedded syntaxes since they are inherently an unsafe transformation. Thus the more Prettier adds them the less reliable it gets. There were already cases where such changes had to be reverted. We can't know who else and how uses the svg template tag.

Similar blocked PRs: #8647, #5993

#5588 is open for proposals.