Improve scheduler

[goccy]

Make validation priority to the highest.
If we write the following options, the order is validationA => ( callA , validationB ) => callB .
(※ callA and validationB are called concurrently )

def { validation {} } // validationA
def { call {} } // callA
def { validation {} } // validationB
def { call {} } // callB

The important thing is that call block is executed after validation block.

[github-actions]

Code Metrics Report

	main (4b71a55)	#227 (959f33b)	+/-
Coverage	65.4%	65.5%	+0.1%
Code to Test Ratio	1:0.4	1:0.3	-0.0
Test Execution Time	7m8s	7m5s	-3s

Details

  |                     | main (4b71a55) | #227 (959f33b) |  +/-  |
  |---------------------|----------------|----------------|-------|
+ | Coverage            |          65.4% |          65.5% | +0.1% |
  |   Files             |             71 |             71 |     0 |
  |   Lines             |          11718 |          11799 |   +81 |
+ |   Covered           |           7669 |           7730 |   +61 |
- | Code to Test Ratio  |          1:0.4 |          1:0.3 |  -0.0 |
  |   Code              |          36608 |          36764 |  +156 |
+ |   Test              |          12836 |          12853 |   +17 |
+ | Test Execution Time |           7m8s |           7m5s |   -3s |

Code coverage of files in pull request scope (71.6% → 71.7%)

Files	Coverage	+/-
grpc/federation/cel.go	0.0%	0.0%
resolver/def.go	93.7%	-0.4%
resolver/graph.go	87.9%	+1.2%
resolver/resolver.go	82.0%	+0.1%
source/file.go	64.8%	+0.3%

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Reported by octocov

[utahta]

LGTM!