Change sanitization rules for script names generation

[Maksims]

Current sanitization rules lead to some weird results as discussed here: playcanvas/editor#1511
And is generally too strict, benefiting those who uses file-name-dash-notation.js for naming files, but some users might use FileNamingLikeClasses.js, and current rules will change it too much, leading to some lower cases letters where unexpected and preventing capital letters in a row (although this is withing Googles Coding Standards which PlayCanvas relies on).

Here is an example of current sanitization results:

file-name	ClassName	scriptName	ok?
ASDASD.js	Asdasd	asdasd	❓
asdasd.js	Asdasd	asdasd	✅
TestScriptA.js	TestScripta	testScripta	❓
test-script-a.js	TestScriptA	testScriptA	✅
TestAIScript.js	TestAiscript	testAiscript	❓
test-ai-script.js	TestAiScript	testAiScript	✅
testAiAiAi.js	TestAiaiAi	testAiaiAi	❓
test-ai-ai-ai.js	TestAiAiAi	testAiAiAi	✅
testScriptA.js	TestScripta	testScripta	❓
test-script-a.js	TestScriptA	testScriptA	✅
testScript.js	TestScript	testScript	✅
test-script.js	TestScript	testScript	✅
helloAI.js	HelloAi	helloAi	❓
hello-AI.js	HelloAi	helloAi	❓
hello-ai.js	HelloAi	helloAi	✅

And here after this PR:

file-name	ClassName	scriptName	ok?
ASDASD.js	ASDASD	aSDASD
asdasd.js	Asdasd	asdasd	✅
TestScriptA.js	TestScriptA	testScriptA	✅
test-script-a.js	TestScriptA	testScriptA	✅
TestAIScript.js	TestAIScript	testAIScript	✅
test-ai-script.js	TestAiScript	testAiScript	✅
testAiAiAi.js	TestAiAiAi	testAiAiAi	✅
test-ai-ai-ai.js	TestAiAiAi	testAiAiAi	✅
testScriptA.js	TestScriptA	testScriptA	✅
test-script-a.js	TestScriptA	testScriptA	✅
testScript.js	TestScript	testScript	✅
test-script.js	TestScript	testScript	✅
helloAI.js	HelloAI	helloAI	✅
hello-AI.js	HelloAI	helloAI	✅
hello-ai.js	HelloAi	helloAi	✅

Fixes playcanvas/editor#1511

[albertvanveen]

Thanks! 👌