Allow setting maxFileAdd via env var

[iowillhoit]

What does this PR do?

Lowers maxFileAdd for non-windows oses

What issues does this PR fix or reference?

@W-12256168@

[mshanemc]

no objections. But don't merge until you fix the pjson version.

Also, recommend writing the release notes and making sure the env gets into the main list at https://developer.salesforce.com/docs/atlas.en-us.sfdx_setup.meta/sfdx_setup/sfdx_dev_cli_env_variables.htm

[mshanemc]

rather than nested ternary, you could do something like

Suggested change

	this.maxFileAdd = batchSize ? batchSize : this.isWindows ? 8000 : 15000;
	this.maxFileAdd = batchSize ?? this.isWindows ? 8000 : 15000;

or just

this.maxFileAdd = env.getNumber('SFDX_SOURCE_TRACKING_BATCH_SIZE') ?? this.isWindows ? 8000 : 15000

or use the "default" 2nd prop of env,

this.maxFileAdd = env.getNumber('SFDX_SOURCE_TRACKING_BATCH_SIZE',  this.isWindows ? 8000 : 15000)

[iowillhoit]

Yea, I generally don't like nested ternaries but I like the combination of a nullish coalescing and a ternary less. Mainly because it is not immediately obvious what is being compared. The code you suggested would not work correctly, it would compare the nullish first and use that result for the ternary. If you want to combine the two operators, you'd need to wrap your ternary in parentheses.

// resolves 'tern-true' 👎
console.log('foo' ?? true ? 'tern-true' : 'tern-false');

// resolves 'foo'
console.log('foo' ?? (true ? 'tern-true' : 'tern-false'));

// resolves ""
console.log('' ?? (true ? 'tern-true' : 'tern-false'));

// resolves "tern-true"
console.log(undefined ?? (true ? 'tern-true' : 'tern-false'));

// resolves "tern-false"
console.log(undefined ?? (false ? 'tern-true' : 'tern-false'));

https://jsfiddle.net/hxjzaq5c/1/

I do like the idea of using the default for getNumber, I will switch to that. Thanks for the suggestion