[6.0] Global.serialize method

[aslesarenko]

In this PR:

• Global.serialize method is added
• global operation serialize() is added and translated to Global.serializer method call
• Global.serialize is properly compiled to ErgoTree (tests added)
• SMethod.explicitTypeArgs added to support serialization of necessary types as part of MethodCall serialization, which cannot be inferred from the MethodCall itself.

[kushti]

There are not enough tests:

• do (de)serialization test for the new methods call in MethodCallSerializerSpecification
• do serialize - deserialize roundtrip test
• test newly supported data types , namely Header and Option[], explicitly , but better to test more , see BasicOpsSpecification in deserialize PR

[aslesarenko]

• do serialize - deserialize roundtrip test

• test newly supported data types , namely Header and Option[], explicitly , but better to test more , see BasicOpsSpecification in deserialize PR

Do you suggest to base this PR on top of #979?

[kushti]

• do serialize - deserialize roundtrip test
• test newly supported data types , namely Header and Option[], explicitly , but better to test more , see BasicOpsSpecification in deserialize PR

Do you suggest to base this PR on top of #979?

Sure, how else can you check the roundtrip . Also, new serializers (Header & Option) are there

[aslesarenko]

Do you suggest to base this PR on top of #979?

Sure, how else can you check the roundtrip . Also, new serializers (Header & Option) are there

Ok, then this can be postponed until:

• [6.0] Merge with refactored SigmaCompiler #987 is merged
• [6.0] Global.deserializeTo[] method #979 is finalized and merged

[kushti]

Do you suggest to base this PR on top of #979?

Sure, how else can you check the roundtrip . Also, new serializers (Header & Option) are there

Ok, then this can be postponed until:

* [[6.0] Merge with refactored SigmaCompiler #987](https://github.com/ScorexFoundation/sigmastate-interpreter/pull/987) is merged

* [[6.0] Global.deserializeTo[] method #979](https://github.com/ScorexFoundation/sigmastate-interpreter/pull/979) is finalized and merged

There is no need to wait for merge of #979. Actually, this PR and #979 will be likely merged about the same time.

[aslesarenko]

There is no need to wait for merge of #979. Actually, this PR and #979 will be likely merged about the same time.

At least tests should be fixed in #979 before I can merge it into this PR.
Also, #987 should be merged into #979.

[kushti]

TODO:

• check and incorporate changes from [6.0] Fix SubstConstants: serialize ErgoTree size #995
• check if a specific serializer w. costing possible / makes sense

[aslesarenko]

• check if a specific serializer w. costing possible / makes sense

Please clarify:

• Which specific serializer?
• what "possible / makes sense" means?

Also, please fix the tests.

[kushti]

@ergomorphic those are notes for myself, the PR is not finished, please review finished PRs! In particular, to fix the tests, #972 with Header serialization should be merged into v6.0.0 branch and then this PR.

[aslesarenko]

@kushti, LGTM, cannot approve my own PR, consider approved.