[lexical-markdown] shouldMergeAdjacentLines as an option

[potatowagon]

Description

normalize markdown was introduced in #6629 . one of the significant behavior change this introduced is merging adjacent non empty lines, according to commonmark spec: https://spec.commonmark.org/0.24/#example-177

it is a welcomed change since that brings lexical's impl closer to commonmark. However to avoid breaking current callsites, im making the normalizedMarkdown an option default to true, so it is easier to rollback incase this new behavior causes a regression somewhere downstream

ultimately, if there is no known usecase to have shouldMergeAdjacentLines = false, will look to deprecate shouldMergeAdjacentLines and have it always be true.

Test plan

shouldMergeAdjacentLines = true

Screen.Recording.2024-09-18.at.6.09.06.PM.mov

---

shouldMergeAdjacentLines = false

Screen.Recording.2024-09-18.at.6.11.26.PM.mov

added automated tests

[vercel]

The latest updates on your projects. Learn more about Vercel for Git ↗︎

Name	Status	Preview	Comments	Updated (UTC)
lexical	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Sep 20, 2024 3:06am
lexical-playground	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Sep 20, 2024 3:06am

[github-actions]

size-limit report 📦

Path	Size
lexical - cjs	29.85 KB (0%)
lexical - esm	29.66 KB (0%)
@lexical/rich-text - cjs	38.3 KB (0%)
@lexical/rich-text - esm	31.55 KB (0%)
@lexical/plain-text - cjs	36.9 KB (0%)
@lexical/plain-text - esm	28.86 KB (0%)
@lexical/react - cjs	40.04 KB (0%)
@lexical/react - esm	32.91 KB (0%)

[potatowagon]

skipping export because:

string -> md -> string
(string)

hello 
world

to (md)helloworld
to (string)helloworld

does not convert back to
(string)

hello 
world

[zurfyx]

shouldPreserveNewLines is a specific flag while shouldNormalizeMarkdown is very high-level, I don't think they play well with each other and the code shows how we have to chain conditions to make it work.

I would consider targetting the specific parts of the MarkDown we don't want to normalize as opposed to the normalize function as a whole which is an internal implementation.

[potatowagon]

shouldPreserveNewLines is a specific flag while shouldNormalizeMarkdown is very high-level, I don't think they play well with each other and the code shows how we have to chain conditions to make it work.

I would consider targetting the specific parts of the MarkDown we don't want to normalize as opposed to the normalize function as a whole which is an internal implementation.

good point, i updated to shouldMergeAdjacentLines instead and placed its in a specific place in normalise markdown