flag(server): refactor flag

[josedonizetti]

Refactor flag sever:

• new tests to validate all flags for CLI
• new tests to validate all configurations
• move from flags/server/* package, into flags/*, like all other flags

[codecov]

Codecov Report

❌ Patch coverage is 71.25749% with 48 lines in your changes missing coverage. Please review.
⚠️ Please upload report for BASE (main@584c3eb). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
pkg/cmd/flags/server.go	87.70%	12 Missing and 3 partials ⚠️
pkg/server/http/server.go	17.64%	14 Missing ⚠️
pkg/server/grpc/server.go	0.00%	9 Missing ⚠️
pkg/cmd/cobra/cobra.go	0.00%	4 Missing ⚠️
cmd/tracee/cmd/root.go	0.00%	3 Missing ⚠️
cmd/tracee-rules/main.go	0.00%	1 Missing ⚠️
pkg/cmd/tracee.go	0.00%	1 Missing ⚠️
pkg/cmd/urfave/urfave.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #5004   +/-   ##
=======================================
  Coverage        ?   29.77%           
=======================================
  Files           ?      234           
  Lines           ?    26216           
  Branches        ?        0           
=======================================
  Hits            ?     7807           
  Misses          ?    17875           
  Partials        ?      534           

Flag	Coverage Δ
unit	29.77% <71.25%> (?)

Files with missing lines	Coverage Δ
cmd/tracee-ebpf/main.go	0.00% <ø> (ø)
pkg/cmd/cobra/config.go	89.38% <100.00%> (ø)
cmd/tracee-rules/main.go	15.44% <0.00%> (ø)
pkg/cmd/tracee.go	0.00% <0.00%> (ø)
pkg/cmd/urfave/urfave.go	0.00% <0.00%> (ø)
cmd/tracee/cmd/root.go	0.00% <0.00%> (ø)
pkg/cmd/cobra/cobra.go	0.00% <0.00%> (ø)
pkg/server/grpc/server.go	55.93% <0.00%> (ø)
pkg/server/http/server.go	34.11% <17.64%> (ø)
pkg/cmd/flags/server.go	87.70% <87.70%> (ø)

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[yanivagman]

LGTM