More granular options to ss01 and alternatives for (== and != and === and !==)

[DominoPivot]

The ss01 option includes these ligatures seemingly inspired by Fira Code's liga:

• == becomes a wide equal sign with no visible gap
• != adds a slash across this ==
• === becomes a stack of three dashes
• !== adds a slash across this ===

I was never fond of this, as it makes = and == less distinguishable and obfuscates the meaning of ===. Thankfully, Fira Code offers an alternative via ss08:

• == merges somewhat but retains a small gap
• != adds a slash across this == but the gap remains noticeable
• === merges somewhat but retains small gaps
• !== adds a slash across the middle = of this ===

It would be nice if these were also available in Monaspace.

That said, this draws attention to a bigger issue: ss01 includes many unrelated ligatures that you wouldn't want enabled in all contexts. For instance, the substitutions for !~, ~~, =~ and ~~ would make no sense in languages where ~ is the binary inverse operator, yet you can't leave them out if you want to enable the substitutions for != and !==.

[jothefiredragon]

I personally am not so much of a fan of the 4 programming ligatures you mentioned.

* `==` becomes a wide equal sign with no visible gap

* `!=` adds a slash across this `==`

* `===` becomes a stack of three dashes

* `!==` adds a slash across this `===`

Thus, I support the proposal for the alternative ligatures to those.