Do not throw 500 on invalid value type in search API

[jarifibrahim]

The search API uses values in the query to generate the SQL query. The backend throws internal server error if a query like foo:123 is sent where foo is of type bool. This PR fixes this issue.

With this PR

• We return Bad Request with error like

  error listing work items for expression '
  {"$AND":[
      { "number": { "$EQ" : "asd" } },
      { "space": { "$EQ" : "981fbeef-aa1f-4429-8301-70dc176079da" } }
  ]}': invalid input syntax for integer: "asd"

  instead of Internal Server Error

Fixes https://github.com/openshiftio/openshift.io/issues/4429 Depends on https://github.com/fabric8-services/fabric8-wit/pull/2322

Todo

• Add missing tests at the repository level. (We have very few tests for the Filter() method at the repository level)

[codecov[bot]]

Codecov Report

Merging #2321 into master will increase coverage by 0.02%. The diff coverage is 75%.

@@            Coverage Diff             @@
##           master    #2321      +/-   ##
==========================================
+ Coverage   70.13%   70.15%   +0.02%     
==========================================
  Files         171      171              
  Lines       16621    16629       +8     
==========================================
+ Hits        11657    11666       +9     
+ Misses       3832     3831       -1     
  Partials     1132     1132

Impacted Files	Coverage Δ
search/search_repository.go	77.57% <100%> (+1.13%)	:arrow_up:
gormsupport/postgres.go	42.42% <60%> (+3.13%)	:arrow_up:
workitem/workitem_repository.go	67.79% <0%> (-0.23%)	:arrow_down:

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