feat: Add `context` in `ParseObject`

[mbfakourii]

Pull Request

• Report security issues confidentially.
• Any contribution is under this license.
• Link this pull request to an issue.

Issue

Added context in the save and create and update functions of the ParseObject class.

Closes: #672

Approach

How to use:

ParseObject object = ParseObject(className);
.
.
.
object.save(context: {
    "key","value"
});

Tasks

• [ ] Add tests
• [ ] Add changes to documentation (guides, repository pages, code comments)

[parse-github-assistant[bot]]

Thanks for opening this pull request!

[codecov[bot]]

Codecov Report

Attention: 2 lines in your changes are missing coverage. Please review.

Comparison is base (088bfbc) 39.60% compared to head (33b761f) 39.64%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #970 +/- ## ========================================== + Coverage 39.60% 39.64% +0.04% ========================================== Files 60 60 Lines 3333 3337 +4 ========================================== + Hits 1320 1323 +3 - Misses 2013 2014 +1 ``` | [Files](https://app.codecov.io/gh/parse-community/Parse-SDK-Flutter/pull/970?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=parse-community) | Coverage Δ | | |---|---|---| | [packages/dart/lib/src/objects/parse\_file\_base.dart](https://app.codecov.io/gh/parse-community/Parse-SDK-Flutter/pull/970?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=parse-community#diff-cGFja2FnZXMvZGFydC9saWIvc3JjL29iamVjdHMvcGFyc2VfZmlsZV9iYXNlLmRhcnQ=) | `68.75% <ø> (ø)` | | | [...kages/dart/lib/src/objects/parse\_installation.dart](https://app.codecov.io/gh/parse-community/Parse-SDK-Flutter/pull/970?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=parse-community#diff-cGFja2FnZXMvZGFydC9saWIvc3JjL29iamVjdHMvcGFyc2VfaW5zdGFsbGF0aW9uLmRhcnQ=) | `28.92% <ø> (ø)` | | | [packages/dart/lib/src/objects/parse\_user.dart](https://app.codecov.io/gh/parse-community/Parse-SDK-Flutter/pull/970?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=parse-community#diff-cGFja2FnZXMvZGFydC9saWIvc3JjL29iamVjdHMvcGFyc2VfdXNlci5kYXJ0) | `1.27% <ø> (ø)` | | | [packages/dart/lib/src/objects/parse\_object.dart](https://app.codecov.io/gh/parse-community/Parse-SDK-Flutter/pull/970?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=parse-community#diff-cGFja2FnZXMvZGFydC9saWIvc3JjL29iamVjdHMvcGFyc2Vfb2JqZWN0LmRhcnQ=) | `94.90% <80.00%> (-0.67%)` | :arrow_down: | ... and [1 file with indirect coverage changes](https://app.codecov.io/gh/parse-community/Parse-SDK-Flutter/pull/970/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=parse-community)

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[mbfakourii]

The error related to Test Flutter beta has been resolved in this PR

[mbfakourii]

Could you add a changelog entry?

Done