fix: handle multiple webform for same doctype

[shariquerik]

If you want to create multiple web forms for the same doctype and allow_multiple is not set.
If the user already submitted a web form before and now is asked to submit again for another webform for the same doctype he will not be able to since the old record already exists and it will be displayed if he tries to hit /new

E.g.
We create separate web forms to get a count of employees coming for the company offsite and we store all the data in the same doctype named Offsite.
At the start of the year, we went on our first trip and created a web form named Bhopal Offsite now again at the end of the year we are planning to go for another trip so need to create another web form named Igatpuri Offsite but since each employee have already submitted a response through Bhopal Offsite webform if we create a new web form for same doctype they will be not able to submit a new response since old offsite record already exist.

Now after the fix, we can add a condition in Webform which will be evaluated and if the record does not exist he/she will be able to submit a new response

[codecov]

Codecov Report

Merging #21220 (38513cc) into develop (cb885a8) will decrease coverage by 0.05%.
The diff coverage is 50.00%.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop   #21220      +/-   ##
===========================================
- Coverage    63.89%   63.85%   -0.05%     
===========================================
  Files          765      765              
  Lines        69326    69323       -3     
  Branches      6261     6261              
===========================================
- Hits         44295    44264      -31     
- Misses       21468    21496      +28     
  Partials      3563     3563              

Flag	Coverage Δ
server	68.91% <0.00%> (-0.03%)	⬇️
server-ui	32.21% <50.00%> (+0.03%)	⬆️
ui-tests	51.51% <ø> (-0.10%)	⬇️

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