fix: make bold and italic tags persist after block conversion (text type)

[vvidday]

Currently, converting between text type blocks (text <-> quote / text->text / quote->quote) results in loss of bold and italic tags

• Modified Lotion.vue::setBlockType to use html content instead of text content when target block is text/quote (solves conversion with no search)
• Modified Block.vue::clearSearch to take into account html content - now if type of block before conversion is text/quote, it will store the html content in addition to the text content, and if the type of block after conversion is text/quote, it will use the stored html content. (solves conversion via search)

video

Tags are still lost when converting to heading types, could potentially find a workaround with the current implementation but @holazz's refactor in #39 will potentially make it much easier (I think we would be able to use the same logic as text blocks)

[vvidday]

Apologies, I made a mistake when rebasing so the commit history is unclear. I'll make a new PR with the same changes.