feat: JSON specs support

[jeroenrinzema]

This PR includes support for JSON specs. JSON files could be included next to HCL files.

semaphore -f config.hcl -f example.json

[codecov-io]

Codecov Report

Merging #170 (b9e9342) into master (7a85a9b) will decrease coverage by 2.27%.
The diff coverage is 77.00%.

@@            Coverage Diff             @@
##           master     #170      +/-   ##
==========================================
- Coverage   82.23%   79.96%   -2.28%     
==========================================
  Files         144      157      +13     
  Lines        6385     6717     +332     
==========================================
+ Hits         5251     5371     +120     
- Misses        761      959     +198     
- Partials      373      387      +14     

Impacted Files	Coverage Δ
cmd/semaphore/daemon/providers/options.go	93.10% <0.00%> (-6.90%)	⬇️
cmd/semaphore/functions/strings/sprintf/sprintf.go	95.00% <0.00%> (ø)
pkg/broker/manager/flow.go	0.00% <0.00%> (ø)
pkg/broker/manager/options.go	0.00% <0.00%> (ø)
pkg/codec/xml/errors.go	100.00% <ø> (+10.00%)	⬆️
pkg/flow/flow.go	98.73% <0.00%> (ø)
pkg/providers/errors.go	100.00% <ø> (ø)
pkg/specs/flows.go	94.64% <0.00%> (-3.51%)	⬇️
pkg/specs/services.go	100.00% <ø> (ø)
pkg/transport/protocol.go	100.00% <ø> (ø)
... and 74 more