Add ability to override quoting style for scalar values

[jpb]

This is a reimplementation of #291 and applies the feedback from the original implementation in #291 (comment), except in two cases:

• the option name has been changed from valueFlowScalars to scalarQuoteStyle as the original implementation was (and my use-case is) not limited to flow values
• I chose to not accept STYLE_PLAIN as a value. This didn't make sense to me as I feel this option should never "downgrade" a values quoting – js-yaml only uses quotes when necessary to make valid YAML so removing single or double quotes would to make the values "plain" would produce invalid YAML. This is also why STYLE_PLAIN will have no effect for double quoted values (as the readme states).

Fixes #290

[puzrin]

Implementation is very dirty:

• multiple value types on input
• strings compare in hot path

What should be done:

• use empty string / ' / " as input.
• normalize input value (string) to number, before run.
• something should be done with option name (see comments in prev commit), need to discuss

[yihongang]

@jpb are you still interested in continuing with this work?

@puzrin could you explain what do you mean by input here? is it the null default value vs the expected string values? with regards to the option name what do you have in mind?

[mansona]

I have just tested this and it's working really nicely 🎉 seems like something that would be good to look to merge

[nicmosc]

What's the status on this? Really need this feature! 🙏🏻

[kevthehermit]

Any movement on this?

[SkinnyFatSumo]

Any chance this feature will come through anytime soon? It'd be very helpful

[rlidwka]

I've added more extensive support for this feature in 7b256d7 (located in dev branch currently).

Closing this as outdated. Thanks for posting this PR, helped to find some corner cases I haven't originally thought of.