Fix: disable page reload when hot is not specified

[byzyk]

• This is a bugfix
• This is a code refactor
• This is a test update
• This is a typo fix
• This is a metadata update

For Bugs and Features; did you add new tests?

No

Motivation / Use-Case

Aimed to fix #1251. As per the issue, the page keeps reloading even if hot option is not specified or false. This PR contains fix which disables page reload when hot: false or not specified or hotOnly: true. To enable page refresh along with HMR one has to explicitly set hot: true.

Breaking Changes

No

Additional Info

I think we can consider adding one more option, something like livereload for use-cases when people don't wanna use HMR but instead prefer to go with a regular page refresh. I didn't do it as I feel it's more like a new feature while I tried to keep this PR as simple as possible.

[jsf-clabot]

Thank you for your submission, we really appreciate it. Like many open source projects, we ask that you all sign our Contributor License Agreement before we can accept your contribution.
13 out of 14 committers have signed the CLA.

✅ shellscape
✅ AlexChaseJones
✅ birdwell
✅ ryanwholey
✅ tbroadley
✅ fwielstra
✅ BenoitZugmeyer
✅ evilebottnawi
✅ sokra
✅ abcd-ca
✅ d3viant0ne
✅ yyx990803
✅ byzyk
❌ Bohdan Khodakivskyi

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[codecov]

Codecov Report

Merging #1275 into master will increase coverage by 0.05%.
The diff coverage is 66.66%.

@@            Coverage Diff             @@
##           master    #1275      +/-   ##
==========================================
+ Coverage   75.72%   75.77%   +0.05%     
==========================================
  Files           5        5              
  Lines         482      483       +1     
  Branches      156      155       -1     
==========================================
+ Hits          365      366       +1     
  Misses        117      117

Impacted Files	Coverage Δ
lib/Server.js	82.02% <66.66%> (+0.05%)	⬆️

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