Promote feature discovery of Source Action

[CsCherrYY]

Currently, the available source actions are in the editor context menu -> Source Action..., which is a little bit hard to be found. Will investigate a proper way to promote the feature discovery of source actions.

A way to expose source actions is to add them to "Show fixes" (looks like a bulb), like eclipse-jdtls/eclipse.jdt.ls#1405 did. In this way, I have created eclipse-jdtls/eclipse.jdt.ls#1842 for hashCode() and equals().

Source Assists:

Source Action	Type Declaration	Field Declaration	Import Declaration	Method Declaration	multiple selection
Generate Constructors	✔️	✔️			✅
Organize Imports			✔️
Generate Getters and Setters	✔️	✔️			✅
Generate Getters	✔️	✔️			✅
Generate Setters	✔️	✔️			✅
Override/Implement methods	✔️
Generate hashCode() and equals()	✔️
Generate toString()	✔️
Generate Javadoc	✅	✅		✅
Change modifiers to final	✅	✅		✅	✅
Generate Tests	✔️			WIP

[nickzhums]

@CsCherrYY for getters/setters, besides field declaration, let's add one for class-level too for batch generation. Eg. a class has 5 fields, click on lightbulb to generate setters/getters all at once

[nickzhums]

@CsCherrYY per user feedback, we should consider adding constructors to class declaration as well

[CsCherrYY]

@CsCherrYY per user feedback, we should consider adding constructors to class declaration as well

I have added it to the plan table. Please see the first row.

[nickzhums]

@CsCherrYY per user feedback, we should consider adding constructors to class declaration as well

I have added it to the plan table. Please see the first row.

awesome!

[nickzhums]

Per survey feedback, "Attach Source" is another action user has requested