Description

Closes #8777.

(Note that this PR currently contains #10706, which is a blocker for this one due to both modifying the same file. Once that PR is merged, this one will be rebased.)

This PR refactors the Latest Posts block to use the supports: { align } flag and adds support for the left and right alignments to the block. Notably, support for those alignments was already implied by getEditWrapperProps in index.js, but due to mistakes in master, the alignments could not be chosen in the editor. This PR also adds an enum property to the align attribute in index.php to prevent invalid alignment classes from appearing on the front-end.

This PR is pretty much the same as #10706, except it is for the Latest Posts block rather than the Archives block.

Types of changes

• Using supports: { align } to add block alignment support to the block.
• Added enum to the align attribute defined in index.php to fix an issue in master where you could set invalid values for the attribute, which would result in invalid classes (e.g. "alignbob") on the front-end.
• Simplified some string concatenation code in index.php and made it consistent with other blocks (e.g. Archives and Categories blocks).
• The block attributes defined in index.php were in a random order; now they are in alphabetical order.

Related PRs

• Archives block: use align supports flag + add wide/full align support #10706
• Cover block: Use supports flag for block alignment #10758
• Latest Comments block: use align supports flag + code cleanup #11411
• Categories block: use supports flag for block alignment + wide align support #13215