feat(provider): fetch resources on provider update

[Chief-Rishab]

• On provider update, code currently doesn't fetch resources. Resource Fetch only happens on provider creation and through fetch resources job. It should ideally happen on provider update also.

• add information like appeal_id, grant_id wherever possible in slack notifier error logs so that it is easy to debug whenever there's an error, along with what type of notification was being tried when it errored out.

[coveralls]

Pull Request Test Coverage Report for Build 4964950600

• 56 of 69 (81.16%) changed or added relevant lines in 5 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.03%) to 75.315%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
core/grant/service.go	15	17	88.24%
plugins/notifiers/slack/client.go	4	6	66.67%
core/provider/service.go	14	17	82.35%
core/appeal/service.go	15	21	71.43%

Totals
Change from base Build 4761564421:	0.03%
Covered Lines:	8006
Relevant Lines:	10630

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💛 - Coveralls