fix spacing issues while refactor-reduce

[vidit-od]

Fixes #4825

In the previous implementation resetEntryDP function was triggered when reduction code action removed any leading constraint from the context. This lead to inconsistent spacing for this scenario.

fixes this by

1. not using the resetEndtryDP function ( fixes removal of space after => )
2. add a normalization function that trims leading spaces

[vidit-od]

while working on this issue i also gathered the following observation that

• Remove redundant constraint does not get triggered while dealing with single constrains. i.e

triggering it on the below example does nothing (But constantly shows warning)

while for example 2 (Below) we do observe expected result from

-- Example 2 before remove redundant constraint
j :: (Eq a, Show a) => a -> a
j x = x

to

-- Example 2 after remove redundant constraint
j :: a -> a
j x = x

i did try and fix this but could not !!
main possible suspect of this behaviour could be lying at \hls-refactor-plugin\src\Development\IDE\Plugin\CodeAction.hs

to be specific findSigOfDeclRanged function possibly returning Nothing on single constrains.

Requesting a look at it if worthwhile @fendor

[fendor]

Looks like the ubuntu 9.12 errors are genuine EDIT: Nope, flaky

[vidit-od]

Error logs stated that it failed due to resource vanish ( broken pipe )

Should i look into it ? ( any possibility of optimisation like call-hierarchy ? )

[fendor]

Error logs stated that it failed due to resource vanish ( broken pipe )

We try to address this kind of error in #4701

Dont investigate, I don't think it is worth it

[fendor]

LGTM, tbh, I am relying on the test suite for correctness, because I can't tell without serious tinkering whether this is correct.

Thank you for fixing this!