Add Eslint curly lint rule

[richardwestenra]

Description

JavaScript allows the omission of curly braces when a block contains only one statement. However, it is considered by many to be best practice to never omit curly braces around blocks, even when they are optional, because it can lead to bugs and reduces code clarity. So the following:

if (foo) foo++;

must be rewritten as:

if (foo) {
    foo++;
}

See https://eslint.org/docs/rules/curly

Development notes

The npm run lint:js task on the command line can automatically fix some of the problems reported by this rule.

QA notes

n/a

Checklist

• Read the contributing guidelines
• Opened this PR as a 'Draft Pull Request' if it is work-in-progress
• Updated the documentation to reflect the code changes
• Added new entries to the RELEASE.md file
• Added tests to cover my changes

Legal notice

• I acknowledge and agree that, by checking this box and clicking "Submit Pull Request":

• I submit this contribution under the Apache 2.0 license and represent that I am entitled to do so on behalf of myself, my employer, or relevant third parties, as applicable.

• I certify that (a) this contribution is my original creation and / or (b) to the extent it is not my original creation, I am authorised to submit this contribution on behalf of the original creator(s) or their licensees.

• I certify that the use of this contribution as authorised by the Apache 2.0 license does not violate the intellectual property rights of anyone else.

[rashidakanchwala]

Looks good. I went through all the if's in the code as well and can confirm all of them now have curly braces