Add --alignment_group_boundary flag to control alignment group splitting

[sjalloq]

Currently, alignment groups for module items, statements, and class items are not broken by blank lines or separator comments. This means statements in logically separate sections (e.g., separated by "// ----" headers) get aligned together.

Add a new flag --alignment_group_boundary with four modes:
none (default), blank-lines, separator-comments,
blank-lines-and-separator-comments

A separator comment is an EOL comment whose body consists of 4 or more consecutive identical characters (e.g., "// ----", "// ====", "/////").

Affects AlignModuleItems, AlignStatements, and AlignClassItems.

[linux-foundation-easycla]

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• ✅ login: sjalloq / name: Shareef Jalloq (9872699)

[sjalloq]

This has been an issue that has bugged me for years so I thought I should just fix it. It allows splitting by block comments such that the following statements aren't aligned.

assign net1 = net2;

// ============================================================
// New Block Comment Divider
// ============================================================

assign net312327837434378347 = net3;